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PATTEKN-MAKING 



BY 

FREDERICK W. TURNER 

M 

AND 

DANIEL G. TOWN 

Instructors in Pattern-Making, Mechanic Arts High School, Boston 



FIRST EDITION' 
FIRST THOUSAND 



NEW YORK: 

JOHN WILEY & SONS, Inc. 

London: CHAPMAN & HALL, Limited 

1914 






Copyright, 1914 

BY 

FREDERICK W. TURNER AND DANIEL G. TOWN 



w~m 



OCT I 19(4 



/ &o 



THE SCIENTIFIC PRESS 

ROBERT ORUMMOND AND COMPANY 

BROOKLYN, N. Y. 



'CI.A879797 
*0, 



PEEFACE 



This volume is not intended primarily for the mature 
pattern-maker, although the authors hope the masters of 
the craft may read it with pleasure if not with great profit. 
It is planned to outline to the younger members of the 
fraternity a general survey of the most suitable materials, 
the special tools, and the fundamental processes of the 
trade, together with the relations of the allied depart- 
ments, particularly those of the foundry. The detailed 
construction of typical patterns has been treated in an 
excellent manner by very competent workmen in the several 
books now published, and still the literature of the craft 
is not as large as the importance of the subject would seem 
to warrant. This book is not intended to supplant any 
of the existing works, but rather to pave the way for a better 
understanding of their technical excellencies. If it accom- 
plishes this result even in a small way the authors will 
be well content. 

iii 



CONTENTS 



CHAPTER PAGE 

I. General Trade Relations and Qualifications of a Pattern- 
maker 1 

II. Foundry and Machine Shop Practice as Determining the 

Type of Pattern 5 

III, Allowances and their Effect on the Pattern. 13 

IV. Tools — Bench, Machine and Special 20 

V. Layouts and Templets 38 

VI. Materials — Construction, Fastening and Finishing 43 

VII. Types of Patterns 54 

VIII. Core Prints '. . 65 

IX. Construction of Patterns 71 

X. Core-boxes and Cores 90 

XI. Skeleton Patterns and Sweeps 102 

XII. Specialization in the Pattern Shop and in the Foundry .... 107 



PATTERN-MAKING 



CHAPTER I 



GENERAL TRADE-RELATIONS AND QUALIFICATIONS OF 
A PATTERN-MAKER 

1. Effects of Specialization. The pattern-maker is a 
modern development, — a part of specialized industry — 
and as such he must be a necessity or he would not be 
tolerated. 

It is highly probable that the original casting was 
accidental; molten metal cooling in a shape which proved 
useful. As time went on, the shapes that could be made 
were brought under control. At first, everything from the 
conception of the form to the production of the completed 
casting was the product of one mind. 

Specialization has divided this into a series of steps or 
processes as follows: designing, drafting, pattern-making, 
foundry work, and machine-shop practice. Each of these 
is again subdivided until we reach our present-day shop 
conditions. In spite of the division, the five general proc- 
esses are dependent on one another to such an extent that 
each must keep the others in mind. 

When work is divided among a group of men, some form 
of expression must be found which all can understand 



2 PATTERN-MAKING 

and which will not require personal contact. Drawing 
has been selected for this purpose and it must be uniform 
in order to be intelligible. 

2. Relation to Foundry Practice. In considering the 
work of the pattern-maker, we see at once that the closest 
connection is with the work of the foundryman, be he 
molder or core maker. Such frequent reference must be 
made to foundry conditions, and such careful attention 
paid to the convenience of the molder and the core maker, 
that it might almost be said that the best place to learn 
pattern-making is in the foundry. While it is not neces- 
sary for a pattern-maker to be a molder, he should be 
familiar with general foundry methods and equipment, 
and should consult frequently with the men who are to use 
the patterns he makes. 

The pattern-maker is merely a tool-maker to the molder, 
and a pattern may be defined as any form or device by the 
use of which a mold may be made. This brings the pattern- 
maker into the general classification of non-producers, in 
the sense that his product is only a means to an end and 
not an end in itself. 

3. Demand for the Pattern-maker. Other wood workers 
such as joiners, carpenters, and cabinet-makers produce 
articles which go into permanent use as made. No matter 
how much the elimination of the pattern-maker may be 
considered desirable, he is apt to stay with us for some 
time to come, and undying fame awaits the man who can 
produce all castings without patterns. Possibly the use 
of permanent molds will dispense with some patterns cf 
comparatively small size, but such molds will never render 
the pattern-maker unnecessary. The pattern-maker who 
is resourceful, who can do a job quickly without assist- 
ance, and who works in harmony with the drawing room 



GENERAL TRADE-RELATIONS AND QUALIFICATIONS 3 

on the one hand and with the foundry on the other hand, 
can always have a job. In this respect he is on a par with 
the skilled mechanic in any line. 

4. Qualifications Necessary. In most trades, the prin- 
cipal qualification of a good workman is to be expert in 
handling the tools of his craft, but the pattern-maker, 
like the designer, is more largely concerned with that kind 
of planning which requires a strong effort of the imagina- 
tion. Such planning must include not only the construc- 
tion of the pattern, but also, before this construction can 
be determined, the method of molding, which must be 
selected from the alternative plans which suggest them- 
selves to a good pattern-maker. This is what makes 
pattern-making an art rather than a trade, for while the 
pattern-maker must be a skilled craftsman, his success 
does not depend very largely on the mere cutting and 
fastening together of pieces of wood. As the draftsman 
has the flat sketch of the designer to make into a flat draw- 
ing, so the molder and machinist have a solid body or form 
from which to make another of somewhat similar shape; 
the pattern-maker, on the other hand, has only a flat drawing 
from which to make a solid pattern or form which may 
bear but little resemblance to the casting which is to be 
produced. This makes the work of the pattern-maker 
more like that of the designer than that of any of the other 
contributors to the finished article. 

No book can make a pattern-maker, yet books may be 
of great assistance to him, and the contempt which many 
workmen have for " book learning " is not justified in the 
minds of the best craftsmen. The work is clean, pleasant, 
varied, and well paid, while the working conditions are 
usually better than are found in other trades. The intel- 
ligence and skill required for such intricate work bring 



4 PATTERN-MAKING 

together a superior set of men whose requirements rank 
with those of the engineer. Among these may be noted 
an ability to draw, a working knowledge of geometry, 
a general acquaintance with machine tools, a good sense 
of proportion, and some idea of the strength of materials. 
If a man can read a drawing as well as the man who made 
it, can appreciate the limitations of the foundry, and can 
also see things from the point of view of the machinist, 
then such a man may aspire to become a pattern-maker 
if his judgment is quick and accurate, if he is self-reliant 
and resourceful, and, most important of all, if he has the 
gift of imagination to see a mental picture of the pattern, 
of the way it is to be used in the foundry, and of the finished 
casting. 



CHAPTER II 

FOUNDRY AND MACHINE-SHOP PRACTICE AS DETER- 
MINING THE TYPE OF PATTERN 

While the pattern-maker does not need to be a molder, 
he must know the general principles underlying foundry 
practice, and, above all, if he is to consult with the molder, 
as he should do on many occasions, he must be familiar 
with the terms used in the foundry. A very brief summary 
of foundry operations, while not attempting to cover the 
practice, will introduce and partially explain the terms 
ordinarily used. 

5. Molding Sand. A mold is usually made by with- 
drawing a pattern from sand, leaving a cavity into which 
molten metal may be poured. This molding sand must 
be able to resist heat and have strength enough to keep 
its shape. It is composed of over 90% silica and about 
6% alumina; the first makes the sand refractory and the 
last gives it strength, when the sticky quality of the alumina 
or clay is brought out by moistening. The addition of 
water to molding sand is called tempering and the result 
is that molding sand as used is somewhat damp. The 
sand just mentioned is not prepared in any way except 
by the tempering referred to and so is called green sand. 
It is not very strong at best, but it is cheaper than any 
other method and a large percentage of casting is done 
in this sand. 

5 



6 



PATTERN-MAKING 



When a stronger mold is required, a coarse fire sand, 
almost pure silica, is mixed with clay water to the consist- 
ency of a very stiff dough. After a mold has been made 
in this sand it must be baked to drive out the water and 
make the mold strong. This makes what is called a dry 
sand mold. 

For very heavy work, a somewhat similar mixture called 
loam, with some chopped straw mixed in, is used. 

6. Flasks. Very little molding is done in which the 
top of the mold is left open; usually a cover of sand is placed 
over the cavity. In order to economize sand and to make 




Fig. 1.— Two-part Flask. 



it possible to move the molds about, boxes called flasks 
are used. The common or two-part flask consists of a lower 
part called the drag or nowel, and an upper part called the 
cope. (Fig. 1.) The drag has a smooth upper surface 
with sockets to receive the flask pins which project from 
the cope. Flasks are sometimes made with more parts 
and are called three-part, four-part, etc., the intermediate 
parts between the cope and the drag being called cheeks. 
The interior parts of the flask are sometimes made in sec- 
tions which can be drawn out sideways and which are called 
drawbacks. This is frequently done in dry sand work. 



FOUNDRY AlsiD MACHINE-SHOP PRACTICE 7 

If the cope is large in area and not very deep proportion- 
ally, bars may be fastened edgewise in the cope (Fig. 2) 
and in addition to this, cast-iron hooks called gaggers are 
wet in clay wash and laid against the cope bars. These 
bars and gaggers are used to prevent drop-outs. 

7. Preparing the Mold. In plain molding in a two- 
part flask, the pattern is placed on a pattern or mold board, 
the drag inverted over it, and molding sand is sifted in 
through a sieve or riddle to cover the pattern. As this 




Fig. 2.— Bars in the Cope. 



sand comes in contact with the pattern and forms the 
face of the mold it is called facing sand. In large work 
and especially in dry sand molding a stronger sand mixture 
is used for facing. The drag is then filled with sand which 
is forced into place with rammers. The ramming must 
be done carefully, not hard enough to lose the porosity 
of the sand, which allows the gases to escape, nor so soft 
that the sand will drop out or be pushed to one side by the 
pressure of the metal. The top of the drag is then struck 
off with a straightedge, a bottom board placed over it, 
and the drag rolled over. To prevent the sand in the cope 



8 PATTERN-MAKING 

from sticking to that in the drag, some sand free from clay 
called parting sand must be sprinkled over the drag. The 
cope is then placed, facing sand is riddled in and the cope 
filled up, rammed, and struck off. If it is thought the gases 
may not pass off through the sand, the mold may be vented 
by pushing a vent wire in several places down through the 
cope nearly to the pattern. As the molten metal must 
pass down through the cope in order to reach the mold 
cavity, an opening called a sprue down to the level of the 
drag must be provided. The cope is then lifted, the patterns 
rapped to loosen them from the sand, and drawn up from 
the drag without disturbing the sand. Channels in the 
surface of the drag, called gates, are cut to connect the 
sprue with the mold cavity. Cores are then set if required 
and are sometimes supported by wrought- or cast-iron 
chaplets, tinned to prevent rust, which might cause an 
explosion. The mold is then closed by replacing the cope, 
clamped or weighted to resist the pressure of the metal, 
and poured from a ladle of molten metal. 

As the metal is heavier than the sand, all loose sand, 
entrapped gases, etc., will rise to the top of the mold. 
Therefore, if a surface must be particularly sound, it must 
be arranged to cast that surface in the drag. 

If a surface is required to be particularly hard, a piece 
of iron called a chill is used as a part of the mold, either as 
a section of the flask (Fig. 3), or set in the mold like a 
core. 

When a pattern is frail, or irregular, especially if a 
large number of castings are wanted, a false cope, match, 
or odd side, of plaster of Paris or of sand mixed with litharge 
may be used in place of a plain mold board. (Fig. 4.) 

8. Deciding upon the Kind of Pattern. When a pattern- 
maker receives a drawing of an article for which a pattern 



FOUNDRY AND MACHINE-SHOP PRACTICE 



9 



is necessary, his decision as to the kind of pattern to be made 
will be governed by many considerations. It is very easy 
to say that the pattern-maker is responsible for the pro- 



iron chill 



Dry sand core 
Mold cavity . Green sand cope 






Green sand .nowelr- 

Fig. 3.— Section of Mold with Chill. 




duction of the finished article with the least possible expendi- 
ture of time, labor, and materials in the pattern shop, 
foundry, and machine shop; but it is not as easy to decide 



Patterns ' 




Fig. 4.— Odd Side or False Cope/ 

which of the many possibilities will prove to be the most 
economical. While the molder may be consulted as to 
the best method from the foundry point of view, it must 



10 PATTERN^MAKING 

be remembered that a good molder can get a mold from 
almost any conceivable shape. One enthusiast is on record 
as saying, " I can mold the pronged horns of an antlered 
buck from the natural pattern as it grew on the animal's 
head." The equipment of the machine shop which is to 
handle the castings must also be kept in mind, but the 
principal, and many times the governing factors are the 
metal to be used and the number of castings wanted. 

In a "one-casting" pattern, the burden of labor can 
safely be thrown on the foundry, and such a pattern would 
be called temporary and ought not to be stored, but de- 
stroyed as soon as used. A pattern to be used infrequently, 
as is the case with a so-called master pattern, must be made 
so that the retention of its shape will be its principal 
feature. A pattern to be used regularly for a long period 
would be called a standard pattern and should be made so 
that strength to resist use and abuse in the foundry would 
be its main feature. 

When the information given on the drawing has been 
absorbed, the different molding possibilities should be 
considered. Note the choice in the case of such simple 
patterns as the plain gland (Fig. 5) and the solid roller 
(Fig. 6). Many times there are no precedents to govern 
the choice, and only a careful consideration of such factors 
as cost of molding, cost of cores, soundness of faces to be 
machined, strength and cost of pattern will bring about 
the combination of greatest efficiency. The modern tend- 
ency toward casting in one piece as contrasted with the 
older practice of bolting on parts tends to make more com- 
plicated patterns. 

The same considerations govern the~ repair of old pat- 
terns, as there is often question as to whether the changes 
required on an old pattern to bring it up to date are not 



FOUNDRY AND MACHINE-SHOP PRACTICE 



11 



more expensive than the construction of a new one. No 
good pattern-maker enjoys making over patterns, even 
those made by himself. It is hard on tools and temper, 










Gland 
Casting 



















\ 










Cope 










Side 










Parting 








\ 


Line 












/ 



































Parting 












Cope Side 






Line 






















i 1 





















Fig. 5. — Possible Patterns for a Gland Casting, 



and the result is never satisfactory from the workman's 
point of view. 

In view of the different governing factors and their 



12 



PATTERN-MAKING 



relative importance, it is not surprising that, with the same 
data, several good pattern-makers might each decide upon 
a different method. As there can be but one best way to 



i Split pattern or whole 
pattern bedded in 



Parting- 



Coped down 




Cover core print 




Parting 



Three-pari? 



Cope side Line 

Fig. 6. — Possible Patterns for a Solid Roller. 



make a pattern, it is evident there should be the freest 
consultation on an important job of all parties concerned, 
in order that the plan finally adopted may represent the 
most advanced ideas to be found in the engineering staff, 
of which the pattern-maker is not the least important. 



CHAPTER III 
ALLOWANCES AND THEIR EFFECT ON THE PATTERN 

9. Allowances. One of the peculiar things about pat- 
tern-making is that certain changes in shape and dimensions 
from those shown in the drawing are necessary in order 
to get a casting which finally will be exactly as shown on 
the drawing. These allowances as they are called are made 
necessary partly by the nature of the metal to be used, 
partly by the nature of the mold to be made, and partly 
by the work to be done on the casting after it leaves the 
foundry. 

The Allowance for Shrinkage is 1 made necessary by the 
fact that nearly all commercial metals shrink somewhat 
in changing from the liquid to the solid state. The amount 
of shrinkage varies with the metal and also to some extent 
with the shape and weight of the casting. The casting is 
usually somewhat smaller than the mold in which it was 
cast, so the pattern must be made a little over the drawing 
dimensions in order to overcome this change in size. In 
the case of cast-iron, it should be noted that hard irons 
shrink more than soft, and that large castings shrink less 
in proportion than light ones. 

Small gray iron castings made in green sand will shrink 
about J" per foot, while large castings in dry sand or loam 

13 



14 PATTERN-MAKING 

will shrink at the rate of tV per foot. What are known 
as malleable iron castings are cast in a hard white iron 
which shrinks about ^" per foot. Such castings are 
usually small and should not be over \" thick. Steel 
castings, which by the way are usually made in dry sand, 
must have an allowance for shrinkage at the rate of \" 
per foot. Castings in brass, an alloy of copper and zinc, 
or in composition, an alloy of copper, tin, and zinc, shrink 
about yq" per foot, while castings in bronze, an alloy of 
copper and tin, shrink about -£2" per foot. Lead shrinks 
a little over J" per foot, but a 4 to 1 alloy of lead and anti- 
mony has no shrinkage and so can be used for making 
duplicates of the master pattern. Type metal also has 
no shrinkage. 

10. Unequal Shrinkage. If parts of the casting have 
sand between them in the mold the shrinkage tends to 
crush this sand when cooling takes place. If this sand 
happens to be a core which is harder than the rest of the 
mold, then the shrinkage cannot take place so readily 
and may thus be less in one direction on the casting than 
in another. A cylinder with a dry sand core, for example, 
will shrink less in diameter than in length for the reason 
that the core checks the shrinkage. 

A change in the thickness of the casting may make one 
part cool faster than another and so throw a heavy shrink- 
age strain on a weak portion. As thin sections cool more 
quickly in the mold than heavy ones, it is sometimes neces- 
sary to uncover heavy sections soon after pouring so as to 
make the shrinkage more uniform. In the case of a pulley, 
the rim being thin, sets first, then the spokes, and finally 
the hub, which tends to draw the spokes inward. This 
may be overcome to a large extent by uncovering the hub 
almost as soon as pouring is completed. If the shrinkage 



ALLOWANCES AND THEIR EFFECT 15 

strain is greater than the elastic limit of the metal, a broken 
casting will be the result, and even though not broken 
in the mold, a casting may be left with such a strain that 
it may fail in service with a load or shock well below the 
ordinary limit of safety. 

This unequal shrinkage often causes warping of a cast- 
ing which, if not possible to overcome by uncovering the 
mold, may be avoided by making the pattern with an opposite 
warp or camber. In general, the heavy side of a casting 
will be hollow: for example, the bottom of a planer table 
or the ornamented side of a thin flat plate. (Fig. 7.) 
The amount of camber necessary can only be determined 




-^Convex 
side 

Fig. 7.— Thin Flat Plates, Unequal Shrinkage. 

by trial, although the necessity for it and the approximate 
amount may be closely estimated. 

11. Draft. If, as sometimes defined, a pattern is a 
form into whose impression in sand molten metal is poured 
to form a casting, it follows that to obtain a perfect casting 
there must be a perfect impression. If the sand is dis- 
turbed when the pattern is drawn, it makes patching nec- 
essary and sometimes leaves sand so insecure that it washes 
into the mold when the metal is poured. A pattern must 
be so made that the large end comes out of the sand first 
and no part must disturb the sand after the pattern starts. 
To accomplish this result a certain amcrant of taper or 



16 



PATTERN-MAKING 



draft is added to the pattern required for the correct size. 
(Fig. 8.) The amount of draft necessary varies with 
the depth of the draw and with the intricacy of the work. 
As it is an extra and adds to the weight of the casting, 
and possibly to the machine work, it is made as small as 
is consistent with easy and rapid molding. When part 
of the pattern is molded in the cope, that part should 
have rather more draft than a corresponding part in 
the drag, for the lifting of the cope usually takes place 



Cope Side 



Patttng 




Fig. 8.— Taper Added for Draft. 



before any very effective rapping can be done, and 
yet the lifting should have no tendency to raise the 
pattern. 

The amount of draft on small, light patterns may be 
about -£2" per inch while on larger work it may be as small 
as §" or even ■£%" per foot. On large work the taper intro- 
duced by the draft becomes noticeable and is often objection- 
able, while the added weight may increase the cost appre- 
ciably. In general it may be said that on unfinished sur- 
faces as much draft as possible should be added without 
interfering with the design. 

12. Allowance for Finish. If the drawing indicates 



ALLOWANCES AND THEIR EFFECT 



17 



that a surface or surfaces are to be finished, it means that 
the outer part of the casting is to be cut away to a definite 
size so as to expose clean sound metal, and an allowance 
equal to the amount to be cut away is added to those 
surfaces and is called finish. (Fig. 9.) On small castings 
which are cast true to the pattern, and which do not warp 
or shrink appreciably, the amount added for finish may 
not be more than ^", but xe" is more common for iron 



Extra finish 
necessary on cope side 



Parting: 




Fig. 9. — Finish where Required Combined with Draft where 
Necessary. 



castings up to 25 pounds made in green sand. Heavy green 
sand work and castings made in dry sand usually have 
an allowance of from f " to |" due to the greater tendency 
to swell and warp as well as to have a rougher surface. 
Large dry sand castings and more especially castings made 
in loam will vary in size even when made from the same pat- 
terns. The pressure of the metal tends to strain the 
mold causing swells to appear on the casting. Uneven 
ramming is a common cause, while the slight difference 



18 PATTERN-MAKING 

between sharp and dull iron may be enough to make a 
change in size. The surfaces on these large castings are 
not as smooth as is the case on smaller work and all these 
factors combine to make necessary an allowance for finish 
of |" to J"- 

Surfaces to be finished should if possible be cast in 
the drag as the metal will be sounder and freer from blow- 
holes. If necessary to finish a surface cast in the cope, the 
allowance for finish should be greater so as to get rid of the 
dirt, etc., which floats on the molten metal and so gathers 
in the cope. 

13. Effect of Rapping. When castings are to fit together 
without machining, the amount of rapping which the pattern 
gets becomes of great importance. In small patterns, 
especially if they are thin and have a short draw, the rap- 
ping may be enough to more than overcome the shrinkage 
and so produce a casting which is actually larger than 
the pattern. In such a case, there is also no need for 
any draft, as the mold is so much larger than the pattern 
that no great care is needed in drawing. 

When castings must be uniform and true to pattern, 
methods of molding are followed which do not require any 
rapping. This usually takes the form of the stripping 
plate which holds the sand while the pattern is drawn. By 
this method also the necessity for draft is removed and a 
pattern can be made with perfectly straight sides. This 
method is somewhat expensive, is usually employed with 
metal patterns, and has its principal use where large 
numbers of castings are wanted which must fit without 
machining. 

14. Allowances for Machining. Sometimes allowances 
are made which do not appear on the drawing and which 
are solely for the benefit of the machinist. Projections 



ALLOWANCES AND THEIR EFFECT 19 

may be cast on for holding, driving,' or for preventing 
distortion while the casting is being machined. The feet 
on piston ring castings and the brace across the crank 
opening of a crank shaft are examples, as well as the 
centering lug on a tee rest casting or on a drill press frame. 



CHAPTER IV 
TOOLS— BENCH, MACHINE AND SPECIAL 

As patterns are usually made in wood, the bench tools 
used by the pattern-maker are largely those of the wood- 
worker, or cabinet-maker, while the machine tools used 
in the preparation of stock are similar to those used in a 
good cabinet-shop. The peculiar character of pattern 
work is responsible for many special tools which do not 
as a rule have a use in any other trade. Only these special 
tools will be illustrated, together with some special rigs 
used on common tools. 

15. Pattern-maker's Tools. The first advice of any 
good mechanic to a man just entering his craft is to get 
standard, high-grade tools and then keep them in the best 
of order. As applied to pattern-makers, this results in a 
good man usually having a kit of personal tools worth from 
one hundred to two hundred dollars. The amount of 
time spent in keeping tools in order, together with the 
personal character of the tools themselves, makes it almost 
a crime to be considered a chronic borrower. 

A man employed on work of fair size needs a bench 
about 8' long by 30" wide and high enough to suit the 
man's stature. The front of the bench should be of maple 
or birch, 2\" to 3" thick, and preferably laid up in strips. 
Such a top can be planed off from time to time and so 
kept in good condition. The back may be £" thick and 

20 



TOOLS— BENCH, MACHINE AND SPECIAL 



21 



slightly lower than the front. This bench should be fur- 
nished with two drawers and a vise of the quick-action 
variety or better yet a pattern-maker's vise (Fig. 10). 
A cast-iron table about 4' by 2' for truing up and assembling 
work is a great convenience. Extra large work can best 
be handled on the open floor and supported on horses or 
trestles of a height to suit the man and the work. These 




Fig. 10. — Pattern-maker's Vise. 



supports should be so carefully levelled that a plumb bob 
could be used. 

The pattern-maker has little use for the ordinary stand- 
ard rule but uses almost exclusively a shrink rule suited 
to the shrinkage of the metal to be used for the casting. 
When master patterns are made it is necessary to allow two 
shrinks. If the working pattern and the casting are to be 
of the same metal, then it becomes double shrinkage for 
that metal, but where, for example, the working pattern 
is to be brass and the casting iron, it means one brass shrink 



22 



PATTERN-MAKING 



plus one iron shrink. These combinations make necessary 
a wide variety in shrink rules which can be had in 
tV 



i // 

16 7 



1 // 

TO , 



Iff 5 // 

8 J 32 J 



3 // Iff 3'f 

16 ; 4= j 8 > 



and J" per foot. The best 



Fig. 11. — Pattern-maker's Knife. 

rules are of steel 12" or 24" long. Wooden shrink rules 
are usually inaccurate and the graduations are coarse. 
In as simple a tool as the knife, the pattern-maker 
uses an unusual shape. (Fig. 11.) The large amount of 
laying out done and the fine whittling, especially in such 




Fig. 12.— The Edge Center. 



situations as spokes of small gears, etc., makes the small 
point shown a necessity, while the shearing cut given by 
the slope of the blade is highly desirable. This awkward 
whittling is also responsible for the knife with a bent blade 
seen in some kits of tools. 



TOOLS— BENCH, MACHINE AND SPECIAL 



23 



When it becomes necessary to strike an arc from a center 
which is located on the edge of a piece of stock, some means 
must be found to hold the point of the dividers cr trammels. 
Clamping another piece of wood against the first is often 
resorted to. The edge center shown in Fig. 12 is much 
handier and is usually more accurate. It should be made of 
brass and the centers carefully located on the lines as shown. 




Fig. 13. — Trammel Points. 



There seems to be no excuse for making a center square 
in the sizes that are obtainable in the market, but large 
circular work, especially large gear work, often needs a 
center square larger than can be bought. In such a case 
a shop-made tool, if carefully constructed, meets all needs. 
It may be well to point out that the angle between the two 
sides of the head need not be 90° as in the commercial 



24 



PATTERN-MAKING 



article; it is only necessary that the edge of the blade should 
bisect the angle of the head, whatever that may be. 




Fig. 14. — Coping Trammel with Cradle. 



Trammel points should be made to fasten on the side 
of a light wooden bar, and one of the points should have a 
fine adjustment. (Fig. 13.) 



TOOLS— BENCH, MACHINE AND SPECIAL 25 

A very useful tool for use where circular portions are 
to intersect is called a coping trammel. (Fig. 14.) It con- 
sists essentially of a base with a fixed vertical spindle carry- 
ing an adjustable rotating head with a sliding pencil or 
scriber. As an aid in holding either round or parted work 
while using the coping trammel or during other laying out, 
cradles or V blocks as shown in Fig. 14, are very desirable. 
They should be made of metal, cast-iron preferred, and laid 
out very accurately. As they are always used in pairs, 
they should be planed up in long lengths and cut into sec- 




gg - 9 -- " - T::i ^g 7 

Fig. 15. — Tool for Drawing Arcs of Large Radius. 

tions, thus insuring duplication. For drawing arcs beyond 
the reach of trammels, the method shown has many advant- 
ages. To draw an arc of given radius from A to B (Fig. 
15) it is only necessary to find the rise of the segment or 
the versed sine of half the angle at the center by the formula 



-i->-G 



V = R — a/ Rr — ( - ) in which V = versed sine, R = radius, 

and C = chord. By making a board as shown and sliding 
it against pins at A and B, the point D will describe the 
required arc. 

A simple tool for laying out hexagons to be worked from 
the round is shown in Fig. 16. The angle between the 



26 PATTERN-MAKING 

edges lying on the face is 60° and the angle between the 
edges lying tangent to the circle is 70° 32', while a line 
which bisects one angle also bisects the other. 

The good pattern-maker has a large assortment of paring 
chisels and gouges, especially the gouges, which are used in 
every known sweep. 




Fig. 16. — Tool for Laying out Hexagons. 

Carving tools are also used on small work and especially 
on stove plate patterns. 

The ordinary planes of the general wood-worker find 
full use although the use of the block plane is minimized 
by the use of a home-made shoot board with a jack plane 
or jointer. This is a step in advance, but the commercial 
tool (Fig. 17) with an iron base and a plane with a cutter 
set at 45° with its edge is far more accurate and permanent. 



TOOLS— BENCH, MACHINE AND SPECIAL 27 

Of the special forms of planes the pattern-maker finds 
use for the rabbet and routing planes as well as for the 
round soled plane which is particularly useful in working 
out core boxes of large radius and fillets from the solid. 
The flexible faced plane (Fig. 18) is useful in smoothing 
up curved surfaces of large radius, either convex or con- 
cave. 




Fig. 17.— Shoot Board. 

The core box plane is one of the best possible examples 
of a strictly special tool. (Fig. 19.) Made for the single 
purpose of working out semi-circular grooves, it performs 
its function admirably when properly set and intelligently 
used. The construction of this tool is based on the geomet- 
rical proposition that any angle inscribed in a semi-circle 
is a right angle, and this same proposition proves the accuracy 



28 



PATTERN-MAKING 



of the common test applied to semi-circular grooves of hav- 
ing the corner of a square follow the curve. (Fig. 20.) The 




Fig. 18.— Flexible Faced Plane. 




Fig. 19. — Core Box Plane. 



edges of the cutters should be exactly in the sides of the 
angle and not project beyond. This makes it necessary 



TOOLS— BENCH, MACHINE AND SPECIAL 



29 



to cut away the sole on the working side about -j%" deep 
and §" wide. (Fig. 21.) Greater depth would give too 




Fig. 20. — Testing; Semi-circular Grooves. 



rank a cut and make sandpapering difficult. The general 
method of use is shown in Fig. 22. The method of start- 




Fig. 21. — Proper Relation of Cutter and Sole of Core Box Plane. 



ing may be by taking out the first chip to a knife line with 
a chisel or by bradding on a thin straightedge for a guide 
for the first cut with the plane, 



30 



PATTERN-MAKING 



The Forstner bit is of great service to the pattern- 
maker as it works beautifully in soft pine. (Fig. 23.) 




Fig. 22. — Semi-circular Groove Partially Worked Out with Core 
Box Plane. 



Its ability to bore on less than half its area as well as the 
flat-bottomed hole due to absence of worm and spurs are 
its chief features. 




Fig. 23.— Forstner Bit. 



For the man working on thin patterns or stove plate 
work, thickness calipers (Fig. 24) and marking calipers 
(Fig, 25) are of great service. 



TOOLS— BENCH, MACHINE AND SPECIAL 



31 



Probably no small tool is at the same time so important 
and so little known as the cornering tool (Fig. 26), which is 
needed more and more in these days of round corners. 




Fig. 24. — Thickness Calipers. 




Fig. 25. — Marking Calipers. 

16. Machine Tools. In spite of the growing tendency 
to use more machine tools, the size of the individual work- 



32 PATTERN-MAKING 

man's kit has not become much smaller although the 
character of the tools has changed somewhat. Many 
of the operations formerly performed by hand are now 
handled on machine tools with a tendency to cut down 
the amount of bench work, but as the old straight opera- 
tions are taken from the bench the added intricacy of modern 
pattern work places new obligations on the pattern-maker 
so that the actual reduction in hand work is not so great 
as is sometimes claimed. 




Fig. 26. — Cornering Tool. 

The trimmer has taken the place of the block plane and 
of the shoot board, and with its adjustable angles, makes 
an almost indispensable tool. 

The circular saw is probably used more than any other 
machine tool. In addition to getting out stock it is used 
for rabbeting, roughing out core boxes, sawing staves, 
etc. 

The jig saw is not to be recommended except for inside 
work which cannot be reached with a band saw. 

The band saw is used almost as much as the circular 
saw and when in good condition and properly handled leaves 
a surface which only needs sandpapering. Every pattern 
shop band saw should have a tilting table and a fence for 
ripping stock. 



TOOLS— BENCH, MACHINE AND SPECIAL 



33 



A boring machine with a tilting table is a great advantage 
in a pattern shop. Small routing cutters such as are 
shown in Fig. 27, can be used in connection with a boring 
machine for sinking surfaces, working fillets from the solid, 
and other operations of a similar character. 

Where much circular core box work is necessary, a core 
box machine will be found to be helpful. The work which 






Fig. 27. — Routing Cutters. 



can be done on one of these machines is limited only by the 
ingenuity of the operator. 

For surfacing work, particularly if large and heavy, 
no machine tool surpasses the old Daniels planer, although 
it is not now in common use. With its cutter speed of 
10,000 feet per minute, it leaves a good surface which is as 
flat as is possible with a machine. 

For surfacing small pieces, but particularly for joint- 
ing edges, the hand jointer or buzz planer is used. This 



34 



PATTEEN-MAKING 



tool has taken the place of the jointer plane as the trimmer 
has taken the place of the block plane. 

The surface planer or surfacer, either single or double, 
is the tool now most used. The pressure of the rolls, how- 
ever, usually results in a surface not as flat as that left by 
the Daniels planer. 



i 

1 — 





Fig. 28.— End Face Plate and Tripod. 



The surface sander has been used for years in cabinet 
work as a finishing tool, but it is just becoming known that 
sandpaper can be used as a cutting tool. The disc grinder 
of the machine shop is beginning to be used with sand- 
paper in the pattern shop. It takes the place largely of 
the trimmer and the finishing planes and is more accurately 
adjusted and more rapid in operation than either. More- 
over it leaves an excellent surface for gluing and is not 



TOOLS— BENCH, MACHINE AND SPECIAL 



35 



put out of commission by running onto a brad. Many of 
the older pattern-makers do not consider the use of a disc 
sander as workmanlike, but it is due to make a greater 
change in the pattern shop than any other modern tool. 




Fig. 29— Hook Tool. 

For turned work there should be at least two lathes, 
one about 10" swing and another about 20" with an end 
face plate and tripod for extra large work. (Fig. 28.) The 




Fig. 30.— Screw Chuck for Rechucking. 



highest speed of the small lathe should be about 3000 
r.p.m. and in general a speed should be used which will 
give a surface speed of about 4000 feet per minute. For 



36 



PATTEEN-MAKING 



the large lathe, probably no tool is of greater use than 
the hook tool. (Fig. 29.) Large built-up face plates should 
be provided which will remain true and on which patterns 
may be mounted. 




Fig. 31. — Center Plates. 

Fig. 30 shows a screw chuck which can be used for 
rechucking. Center plates, as shown in Fig. 31, may be 
used for heavy split work, while lighter work can be held 
by steel rings, by ordinary pinch dogs, or by corrugated 
fasteners. (Fig. 32.) 




Pinch dogs 



Steel ringa 



Fig. 32. 



All machine tools require care to keep them in good 
condition and due to the high speed of all woodworking 
tools, the bearings should receive much attention. They 



TOOLS— BENCH, MACHINE AND SPECIAL 37 

should be kept well lubricated and not allowed to become 
loose. No machine tool should be used without such guards 
as do not interfere unduly with its operation. The buzz 
planer particularly should be equipped with a safety 
cylinder and a guard to cover the throat of the machine. 

17. Shop Conditions. Nothing is gained by keeping the 
shop equipment down, by crowding either men or tools, 
or by lack of air and light. Men waiting for a chance at 
a machine are costing the concern money as well as form- 
ing bad habits. Cramped quarters are always undesirable, 
especially on fine work with edge tools, and the crowding 
of machine tools is not only conducive to slow operation, 
but is positively dangerous on account of the chance for 
interference. 

Good ventilation is necessary to keep men in condition 
to work effectively, while good light is not only desirable 
for the production of fine work but is also one of the best 
preventives of accidents. Plenty of air without drafts 
and plenty of light, from above if possible, should be the 
rule in every up-to-date pattern shop. 



CHAPTER V 
LAYOUTS AND TEMPLETS 

As the choice of the particular method of molding 
to be used and the allowances for finish and draft may make 
the pattern have but little resemblance to the drawing 
from which it is to be made, either in shape or in dimensions, 
it follows that some method of recording this new shape 
and these new dimensions must be followed. Usually 
the drafting room makes drawings of the finished machine 
and its various parfe for the benefit of the machinist, but no 
drawings of the patterns are furnished for the pattern- 
maker. 

18. Layouts. If the pattern-maker thinks he needs a 
drawing of the pattern he mast make it himself. He wants 
it to be in a form which will allow of ready consultation 
and which will keep its shape. As paper changes in a marked 
degree with the amount of moisture present, he uses wood, 
usually white pine, as a material better suited for a depend- 
able record as well as to the tools he is accustomed to use. 
In order to have his record available for direct reference 
as well as to avoid the necessity for putting on dimen- 
sions, he makes his drawing full size and uses the appropriate 
shrink rule in laying it out. The result is called a layout 
and is the most important step in pattern-making, for it 
not only shows the method of molding to be used, and the 
allowances to be made, but may also be used to show the 
details of construction. 

38 



LAYOUTS AND TEMPLETS 39 

As the layout is made on wood and by a man who is 
more accustomed to wood-worker's tools than to those 
of a draftsman, we find the T-square and triangle replaced 
by the marking gage and try square, and the compasses 
by the dividers, while the knife takes the place of the pencil. 
In using the marking gage for lines parallel to the trued 
edge of the layout board, every setting must be checked 
up by the shrink rule, for the graduations on the marking 
gage are standard. The spur of the marking gage should 
be set so as to make a line as nearly like a knife line as is 
possible, a fine line being as necessary in laying out on 
wood as is the case on paper. 

The same knowledge of geometrical construction that is 
necessary in drafting room practice is needed by the pattern- 
maker in making his layouts. The same degree of accuracy 
is also needed; layouts containing errors in drawing being 
as bad as blue prints with false dimensions. 

In using a layout, dimensions are taken off directly 
by the same shrink rule that was used in making it, or by 
dividers applied directly to the points to be used. 

19. Use of Pencil and Colors. The use of a pencil 
in making a layout should not be allowed, but when the 
layout is completed, a medium hard, chisel pointed pencil 
should be used to emphasize the lines made by the knife, 
gage, and dividers. If cross hatching is to be done, it 
should be free hand with wavy lines. Tinting with colored 
pencil or chalk is also resorted to. Lines which illustrate 
methods of construction should be clearly differentiated 
from those of the pattern proper. To make these pencil 
lines stand out clearly as well as to keep the layout clean, 
a single coat of orange shellac should be applied. 

20. Specializing. Some years ago, one man made each 
pattern complete from the receipt of the blueprint to the 



40 



PATTERN-MAKING 



delivery of the pattern to the foundry. The first tendency 
toward specialization was seen in turning over the putting 
in of fillets, sandpapering, and shellacking to younger 
men or apprentices. More recently there seems to be 
in evidence a tendency to give over the making of the lay- 
outs as a specialty to one man, or, in the case of some small 
shops, to the foreman. Then again, some shops are turning 
over the getting out of stock to specifications to a mill 
gang, so there is left but one other stage in pattern con- 

l 





Fig. 33. — Marking Templet for Segments and Outlines Marked 
on Stock. 



struction, namely, the actual building of the pattern out 
of stock already gotten out and in accordance with a 
layout already prepared. To be considered a good crafts- 
man, one should be well trained in all these departments, 
but the greatest responsibility seems to lie in layout making. 
21. Templets. When getting out stock for a pattern, 
it often happens that several pieces of the same shape, 
although possibly of varying thickness, are required. The 
shape of these pieces usually allows for subsequent work- 
ing to finished form and so is not particularly accurate. 
In order to duplicate these pieces rapidly, it is customary 



LAYOUTS AND TEMPLETS 



41 



to lay out the shape on thin wood and cut to form. This 
makes what is known as a marking templet. By running 
a pencil around this outline, the shape is quickly laid out 
on the wood to be used and the pieces can then be band sawed. 
Waste of stock can often be lessened by reversing the tem- 
plet as shown in Fig. 33. • 

While a pattern is under construction, many tests must 
be applied to make sure the work is progressing in accordance 
with the layout. When it is merely a question of diameters 




Fig. 34. — Form Templet for Sphere. 



or of surfaces which can be tested with a straightedge 
or square, no special tools are necessary, but it often happens 
that a curved surface or an irregular outline is to be made 
which cannot be tested with any of the ordinary tools. In 
such cases it is necessary to make a reverse of the surface or 
outline which can be applied directly to the pattern. These 
outlines are called form templets. They are laid out very 
carefully on thin wood, band sawed close to the line and 
finished with knife, chisel, and file. Even with thin wood 



42 PATTERN-MAKING 

it is difficult to make the edges exactly square and as the 
outline must be exact, the templet is backed off (Fig. 34) 
until the edge to be applied to the work is about ^-" thick. 
When the pattern is close to shape, this thin edge may be 
rubbed with a soft pencil before applying the templet to 
the pattern, so a black spot will indicate the portion of the 
work which needs reduction. 



CHAPTER VI 

MATERIALS— CONSTRUCTION, FASTENING AND 
FINISHING 

The material used in the construction of a pattern 
depends very largely on the way and manner in which it 
is to be used. For example, a temporary pattern from which 
only one or two castings are to be taken, does not need to 
be made of as good material or to be constructed in such a 
careful manner as would be the case if long life and constant 
use were contemplated. 

22. Pattern Materials. The materials most often used 
for making patterns and named in the order of their general 
use, are wood, cast-iron, brass, aluminum, and plaster 
of Paris. The use of wood for this purpose is so general 
that a pattern-maker is usually understood to be a wood- 
worker. The advantages of wood as a material for pat- 
terns as compared with other materials are that it is light 
and portable, easy to work or to alter, and comparatively 
cheap. Its disadvantages are that it tends to change its 
shape, is so soft as to be liable to injury, and, being used 
in many small pieces, is apt to come apart if great care is 
not taken in construction. Of these defects, the tendency 
to warp is the most vital, as changes too small to be visible 
might seriously affect the castings. Therefore those woods 
which have the least tendency to change their shape are 
chosen for pattern work. Only three are used to any great 

43 



44 



PATTERN-MAKING 



extent: white pine, cherry, and mahogany. Any wood 
which has been quarter sawed, i.e., sawed so that the annual 
rings are nearly at right angles to the face of the board,, 
(Fig. 35), is less liable to warp than that which has been 





Quarter sawed 



Bastard sawed 



Fig. 35. 



straight or bastard sawed. In drying out, the rings tend 
to become straight so the heart side of a board will become 
rounding or convex. (Fig. 36.) In very small, particular 
work it pays to select a board which has the rings running 
directly through it. 




Concave side 



Fig. 36. — Warping. 



The best pine probably is clear Michigan pine, although 
California or sugar pine is used by many, especially on 
large work. Strictly speaking, the latter is not a true pine 
but looks and works much the same. The cherry used is 
from the large trees of the Middle West. It is much harder 



MATERIALS 45 

than pine, not so straight grained, cannot be had in such 
large, clear lengths, but is used for small patterns subject 
to continual hard usage. Most of the mahogany is from 
Mexico near the Gulf of Campeche and would be more 
properly called bay-wood as it is much lighter and softer 
than a true mahogany. True mahogany would not be a 
suitable wood for patterns as it is too heavy and too hard 
to work readily. This bay-wood is somewhat harder than 
white pine, can be worked almost as easily and is obtain- 
able in long, clear lengths, but it is the most expensive of 
the three woods mentioned. It is also an open grained 
wood and requires extra treatment to obtain a clean, smooth 
surface. 

23. Glue. In the construction of patterns, the various 
parts have to be held or fastened in a way which is some- 
times temporary and sometimes permanent. Probably 
no one method is more used than that which involves the 
use of glue. The pattern-maker recognizes two kinds: 
cold or liquid glue, and hot glue. The first is usually a 
fish glue kept liquid by the addition of acetic or of nitric 
acid. It hardens slowly, does not chill as readily as hot 
glue, and is valuable where construction is complicated 
and the work of assembling the parts is slow. It is not 
considered to be as reliable or as strong as hot glue. 

The best hot glue is made from hides, for which reason 
it is sometimes called animal or hide glue, and comes to the 
pattern shop in the form of hard, semi-transparent sheets. 
These sheets are broken up, soaked in cold water for about 
twelve hours, then cooked slowly until perfectly fluid. 
Some pattern-makers perfer to use ground glue and thus 
save nearly all the time of preliminary soaking. Adultera- 
tion is so much easier to conceal in ground than in sheet 
glue, that it is unsafe to use the former unless one is sure 



46 



PATTERN-MAKING 



of his source of supply. The better the glue the more water 
will be absorbed, thus adding to the quantity. This glue 
should be used hot and comparatively thin, and should 
not be chilled by cold wood or by drafts of air. The com- 
bination of a warm room, hot thin glue, warm wood, and 
rapid work produces the best results. When making up 
a glued joint, all the surplus glue should be removed either 
by rubbing the joint by hand or by clamping with hand 
screws or cabinet clamps. Steel pinch dogs such as are 
I 




Fig. 37.— Pinch Dog. 



shown in Fig. 37, are also used to hold work while glue is 
hardening. The bevel being on the inside tends to close 
the joint. The holes made are the principal objection 
to this type of clamp. 

24. Sizing. The end grain of wood absorbs glue so 
fast that it is always well to give it a preliminary coat of 
glue called sizing, which closes the pores and allows the 
regular coating to unite the pieces. If a large amount 
of end grain is to be glued, it is profitable to use a thinner 
and cheaper glue for sizing than that used for its holding 
power. 



MATERIALS 47 

25. Fasteners. The ordinary nail, either cut or wire, 
is used but little in the construction of patterns, but brads 
are used quite extensively. They are usually long and slen- 
der, such sizes as §"-20 and 2"-15 being common. As 
brads are used principally as a reinforcement to glue, the 
holding power of a large head is not needed, while the hole 
made by the comparatively small head is more easily con- 
cealed. As a temporary fastening while gluing, especially 
on thin light work, the long and slender looking glass tack 
is well suited. The head is of no consequence, but the needle- 
like point enters easily with but little tendency to split 
the wood. Brads as a permanent part of a pattern are the 
despair of the man who has to repair or to alter it, and are 
the cause of many damaged tools and tempers. 

Screws not only make a pattern which is stronger, 
but also facilitate repairs and changes. Round head screws, 
the length of which is measured under the head, are not 
much used in pattern work; the flat head screw, whose 
length is measured over all, is much more common. Here 
again a long and comparatively slender fastening is pre- 
ferred, in such sizes as 2"-No. 12 or l"-No. 10. 

26. Dowels. When two parts of a pattern are not 
fastened together permanently, but simply held so that there 
can be no side motion, it is customary to use dowels for thus 
locating the parts. These dowels are usually round and of 
either wood (birch or maple) or of metal (brass or cast- 
iron) . Those made of wood fit into holes bored in the pat- 
tern, while metal dowels have metal sockets. Large dowels 
for heavy work are provided with a plate for the dowel and 
one for the socket and these plates are let in flush with the 
surface of the pattern. (Fig. 38.) Met:al dowels cost 
more than wooden ones and are more expensive to put 
in place, but they do not shrink or swell and stand much 



48 



PATTERN-MAKING 



more wear than those made of wood. Moreover, the plates 
may also have holes for rapping and drawing and thus 
save the wear and tear on the pattern caused by the ordinary 
draw nail or iron which is simply driven into the wood. 

As dowels are usually placed near the ends of a pattern, 
the plate of either cannot be used for drawing, if that opera- 
tion is to be done by one hand. For that purpose, a 
rapping and drawing plate having no dowel would be inserted 
at the center of gravity of the pattern, so that it would 
balance when drawn. On large work three or more plates 




Fig. 38. — Dowel-plates. 



might be used, with chains leading from the draw, irons 
and the whole lifted by a crane. 

27. Corners. Probably the greatest difference between 
the castings of fifty years ago and those of to-day lies in 
the still increasing use of the round corner. The round 
outside corner looks better, handles better, and molds bet- 
ter than a square one, and this is also true of the inside cor- 
ner. The greatest benefit of the round inside corner cannot 
be seen, however, but consists of the production of a sounder 
and stronger casting. The cooling strains produce an 
effect similar to that shown in Fig. 39. 



MATERIALS 



49 



The round outside corner is worked down from the 
easily made square corner. It is also easier to make a square 
inside corner than to work it out round from the solid. 
To avoid this working out, it is customary to make a sharp 
inside corner and afterward put in the quarter round in 
the shape of a fillet. This may be of wood, wax, leather, 
putty, or lead. On long straight work a wood fillet is easily 
applied, but it cannot be worked around curves of short 




mm 



ummmim^ 




Fig. 39. — Section of Casting Showing Weakness due to Sharp 
Inside Corner. 



radius. It is made with an angle of a little over ninety 
degrees so that the feather edges will lie closely against 
the sides. (Fig. 40.) Small brads hold it in place while 
the glue or shellac used to fasten it has time to set. 

Pure beeswax is used for fillets of small radius, as it 
is easily pushed into place and shape by a fillet tool of 
proper size. The best fillet tool is a shank carrying a 
steel ball which may be warmed over an alcohol lamp. 



50 



PATTERN-MAKING 



In the absence of the steel ball or of the lamp, a piece of 
maple dowel rounded on the end and soaked in machine 
oil makes a good substitute, although it takes a little more 
pressure. The presence of rosin in the beeswax makes it 
harder, but so brittle that it cannot be worked satisfactorily. 
It is easier and more economical to use it in the form of 
wax wire made of proper size by a wax gun in which warmed 
wax Js pushed through a hole by a plunger. Wax makes 




Applied 



Fig. 40.— Wood Fillet. 



a comparatively soft fillet and one which will stick to the 
sand unless it is well covered with shellac. It holds better 
if applied to the pattern after the first coat of shellac has 
been rubbed down. 

Leather is probably the most satisfactory material for 
fillets as it is fairly hard, flexible, light, and is easily and 
permanently applied. It is cut in strips in the shape 
shown (Fig. 41) and is rubbed into place with a fillet tool 
after shellac has been applied in the corner and to the 
back of the fillet. Putty and lead are cheap especially 



MATERIALS 



51 



for large fillets, and are easily applied, but both tend to jar 
out, putty especially. 

28. Marking Patterns. Patterns should be marked 
in some way for identification, and usually this mark is 
reproduced in the casting. Firm names, patent dates, 
and directions often appear in raised letters on the cast- 
ing. All these must be applied to the pattern in the form 
of pattern letters which should have plenty of draft. If 
very small, they may be embossed on a thin sheet of alu- 




Applied 



Fig. 41.— Leather Fillet. 



minum. Larger letters and figures are made of a soft lead 
alloy or of brass, Roman and sharp Gothic being the usual 
styles. The soft alloy allows them to be placed on curved 
and irregular surfaces. Metal patterns usually have brass 
pattern letters which are soldered on. 

29. Finishing. After the tool work on a pattern has 
been completed, it is smoothed up with sandpaper. This 
consists of quartz sand or of pulverized glass glued to a 
paper backing. The grades run from No. 00, which is 
very fine, to No. lj, which is certainly as coarse as should 
ever be used on a pattern. Sandpapering by hand should 



52 PATTERN-MAKING 

never be used to change shape, but simply to remove tool 
marks. It is not a cutting tool, as its action is purely 
that of scraping. 

A pattern with the bare wood exposed would not stay 
in shape because the absorption of moisture from the damp 
sand would cause warping. Neither would it draw easily, 
as the sand would cling to the wood. In order to overcome 
both these objections, patterns are covered with a varnish 
which presents a hard, smooth, and impervious surface. 

Oil varnish is not commonly used on patterns as it 
takes too long to harden. Spirit varnish, or gum shellac 
dissolved in alcohol, dries much quicker and is hard enough. 
Grain alcohol is best, denatured alcohol is very good, and 
wood alcohol very poor. The yellow flake gum shellac, 
when cut in alcohol, produces what is called orange shellac. 
When it becomes dark and dirty from age and use, the color 
may be restored by stirring in a small quantity of pulverized 
oxalic acid. Different colors are produced by adding 
colored pigments or aniline dyes to the orange shellac. 
Lampblack, first made into a paste with alcohol, will give 
black shellac. Other colors used are red, green, and yellow. 
There is no generally accepted standard for the different 
colors, but core prints and core outlines on the drag part 
of the pattern on the one hand, and the surfaces concealed 
by loose pieces on the other hand, must have colors which 
distinguish them from the pattern proper. Paint is some- 
times used for pattern protection. Two or three coats 
give a thick, hard coating, but the time taken for drying 
is so great that it is not often used. 

As alcohol evaporates rapidly, there should be tight 
covers on shellac pots with some arrangement so that the 
brushes will hang in the shellac and not rest on the hair or 
on the bristles. 



MATERIALS 53 

Iron patterns should be first rusted by a solution of 
sal ammoniac or ammonium chloride with water. The 
pattern is then rubbed down and a hard wax is applied by 
warming the pattern and flowing the wax over it. When 
the surplus wax is removed the pattern will have a smooth 
glossy surface which will part from the sand much easier 
than the bare iron. 



CHAPTER VII 

I 

TYPES OF PATTERNS 

The different methods of molding, the variations in 
pattern construction, and the features desired in finished 
castings all combine to make a large number of molding 
possibilities. The pattern in any given case may be any 
one of several different types, and it is impossible to say 
without a knowledge of all the conditions, just what type 
of pattern should be. used. It will probably be better for 
the purposes of this volume to mention the types by name, 
and show such patterns as will illustrate them. 

30. Determining the Type of Pattern. The factors 
which combine to determine the type of pattern may be 
classed under three heads; those of the pattern shop, those 
of the foundry, and those of the machine shop. The 
convenience of any particular trade should not be the 
controlling influence in the choice of the type of pattern. 
The making of the pattern is only one step toward the 
production of satisfactory castings at minimum cost. It 
will be noted that the character of the casting is placed 
before its cost, because an unsatisfactory casting is dear at 
any price. 

The machine shop views castings from two angles; 
on the one hand, a casting must be easy to hold, and on the 

54 



TYPES OF PATTERNS 55 

other hand, it must be easy to work. The strength of the 
casting and its fitness for the work it has to perform is a 
matter decided by the designing department before the 
patterns are made. The foundry is principally concerned 
with the method of molding. It naturally wants the 
pattern made in such a way that the labor cost of getting 
out the casting will be reduced to a minimum. The pat- 
tern shop is concerned primarily with meeting the require- 
ments of the foundry and the machine shop with the least 
expenditure possible for labor and material. Thus we see 
that no one of the three shops can expect to have its own 
convenience followed out in full. There should be a con- 
sideration of the convenience of all, before the pattern 
is started. 

31. One-piece Patterns. Solid patterns in one piece 
are sometimes made from such materials as clay, wax, 
sand, or plaster of Paris, but they are not permanent and 
are usually used only where a single casting is desired of a 
comparatively simple piece. In some cases the nature 
of the material makes it necessary to destroy the pattern 
in order to get a casting from it. We are dealing more 
particularly with permanent patterns which are usually 
made of wood. 

The simplest type is usually known as a one-piece 
pattern, meaning that the pattern is made from a single 
piece of wood. Such patterns are usually cheap because 
no time is taken for building them up, but they are sub- 
ject to the disadvantage of being apt to warp, and in the 
case of a large pattern, would require too much stock even 
if the size to make a solid pattern could be obtained. As an 
example of the one-piece pattern we may consider a small 
cylinder (Fig. 42). The diameter may be relatively great 
or small and the method of making the pattern would 



56 



PATTERN-MAKING 



depend, somewhat, on this relation. Usually the pattern 
would be made so as to have the shortest draw possible. 
If the cylinder is to be molded horizontally, it may be bedded 
into the drag, or the mold can be coped down to the part- 
ing line on the pattern. If it is molded vertically, the 
complete mold would be in the drag. The decision as to 








Fig. 42. 



Fig. 43. 



which type of pattern to make would turn largely on the 
depth of draw involved. Such a pattern molded horizontally 
involves extra labor on the part of the molder, but would be 
justified in case very few castings were required. 

32. Split Patterns. If many castings of the above cylin- 
der were required, it would be better to make a split pattern 
(Fig. 43). This involves more labor for the pattern-maker, 
but it gives the molder a chance to make his parting with 
less labor, and as this has to be repeated many times, the 
extra work of the pattern-maker is justified. 

33. Use of a Follow Board. Another type of pattern 
is made on a follow board (Fig. 44). This is done for one 
of two reasons; to give the molder a chance to make his 



TYPES OF PATTERNS 



57 



parting readily with a pattern of irregular outline or, to 
support a thin pattern, which might be injured during ram- 




Fig. 44. — Section of Follow Eoard. 

ming up if it were not carefully protected. Stove plate work 
is an excellent example of this last requirement. (Fig. 45.) 




Fig. 45.— Pattern for Range Door. 



34. Built-up Patterns. A built-up pattern, that is, 
one made of several pieces, may be made in that way for 
several reasons. It may be to save time, to economize 



58 



PATTERN-MAKING 



stock, to get a stronger pattern, to prevent warping, or 
for any combination of these reasons. A frail pattern 




Loose piece 

Fig. 46. — Frail, Irregular Pattern. 



(Fig. 46) would certainly be made in this way. If made 
from a single piece, it would not be strong enough to stand 
ramming and it would certainly warp badly. A more 




Fig. 47. — Simple Pattern. 



stocky pattern (Fig. 47) could be made from a single piece 
as far as strength is concerned, but probably it would not 
stay in shape. 



TYPES OF PATTERNS 



59 



35. Cores. A piece which is to be cast with a hole 
in it may be made in either of two ways. By the simpler 
method there is a hole in the pattern with sufficient draft 
to prevent the sand from being disturbed. (Fig. 48.) 
As the sand which causes the hole is a part of the mold 
proper, it is called a green sand core, or, as it is some- 
times expressed, the pattern '' draws its own core." This 





..,.Cope.Side.....^ 












•">.;., 








Parting 




i ;:;•-■•* •••:'.'•; 




l-H-l/.l w^-rrftTT 

': •' .• . ' .'• j.'I'ine;* 


Mold 


■ T -\ '.'•'•*. " 


Mold 




Cavity 


^••••'f.l'V-P 010 ■■'. - » 


Cavity 

1 




I J 


••'•'•;.:.' *•'•..'•'.• 


j 


' • ' > .• . ■ y 



II 



Fig. 48. — Green Sand Core. 



method is often used when the hole is vertical and of a 
comparatively large diameter so that the core is well sup- 
ported. A pattern which draws its own core is usually 
cheaper for both the pattern-maker and the molder, the 
casting is easily cleaned, and the surface is comparatively 
smooth. 

On the other hand, if the hole is to be small or if it 
is to be at an angle to the vertical, a dry sand core is used. 
(Fig. 49.) This makes it necessary for the pattern-maker 
to make a core-box and the core-maker in the foundry to 
make a core which must be set by the- molder. Molds 



60 



PATTERN-MAKING 



requiring cores are more expensive and there is some dan- 
ger of injuring the mold when closing on the cope. The 
dry sand core makes a casting more difficult to clean and 
leaves a rougher surface. For all these reasons the green 
sand core method is preferable where it can be used. 

......... •-...: Cope Side... ....... ........ . r 



A '.:'.....' 




/will 




1'arti'ng- 


l^.j:-l:.i'.i-M.J: : l. .;l;. 


TfVri Vi r 

Mold 
Cavity 

1 


■?-'t *".■*' ^r--* 

•••'.•'v. Core /.:••. •.y.; 

£.,■*■*: .. # v *■* 

■ * ■.*& * ••'^ 


Mold 
Cavity 

J 


y}::'>^X;yflAti(i 


••>••:••-•.•••-.•.■■;•.•: 









Fig . 49.— Dry Sand Core. 



36. Part Patterns. Under certain conditions it is 
only necessary to make a part pattern. When the com- 
plete mold can be divided into a number of exactly similar 
parts, a pattern for one part may be used successively 
until the whole mold is completed. (Fig. 50.) This saves 
stock and time for the pattern-maker and in many cases 
is more convenient for the molder. Sometimes a part 
pattern is made to use in connection with a skeleton pattern 
or to make a part of a swept-up mold. 

37. Skeleton Patterns. When the surfaces of a large 



TYPES OF PATTERNS 



61 



pattern consist principally of true arcs or of plane surfaces 
a skeleton pattern may be made which is merely an out- 
line of the casting to be produced. (Fig. 51.) The sand 
surfaces can be struck up by means of strickles or strikes 
which are guided by this outline. On large work this gives 




Fig. 50. — Pattern for Hub and Spokes, 6-armed Sheave, Rim 
to be Swept up. 

great economy of time and material in the pattern shop 
which more than offsets the extra labor of the molder. 

38. Metal Patterns. When small castings are to be 
produced in large quantities, metal patterns are prepared, 
gated, and used in connection with a molding machine. 




Fig. 51. — Skeleton Pattern. 



A wooden master pattern is first made with an allowance 
for two shrinks; one for the metal of the working patterns 
and one for the metal of the desired castings. The castings 
for the metal patterns must be finished very carefully and 
then joined together to form a gate. (Fig. 52.) The 



62 PATTERN-MAKING 

metals* used for these gated patterns are cast-iron, brass, 
white metal, and aluminum, which are named in the order 
of their desirability. 

39. Special and Irregular Patterns. If it is necessary 
that a casting should show little or no draft, as is the case 
in cast gear teeth, a pattern without draft may be made 
and drawn through a stripping plate. (Fig. 53.) This 

I 




Fig. 52.— Gated Patterns. 

holds the sand when the pattern is being drawn and thus 
makes draft unnecessary. Such a stripping plate, if it is 
to be used constantly should be made of metal and a metal 
pattern is also desirable. This work is usually put on a 
molding machine which draws the pattern mechanically. 
When a pattern is irregular in outline so that the part- 
ing line cannot be made easily, an odd-side (Fig. 4) 
can be made of a mixture of molding sand and litharge in 
the proportion of eleven to one which is moistened with 



TYPES OF PATTERNS 



63 



Patterns in position, 
for molding: 




Patterns drawn down 
through stripping plate 




Fig. 53.— Molding Machine Arranged to use Piston Patterns. 



64 PATTERN-MAKING 

boiled linseed oil. When the pattern is bedded to its part- 
ing line in this mixture we have, in effect, a follow board. 
The odd-side becomes very hard and the pattern may be 
removed and replaced as many times as are necessary. 

Another method of producing this result is to place the 
cope and drag parts of the pattern on opposite sides of a 
heavy plate which is guided by the pins of the flask. This 
forms what is called a match plate (Fig. 54) and is more 




Fig. 54. — Match Plate for Four Teakettle Spouts. 

expensive but more accurate and permanent than an odd- 
side. 

40. Chilled Castings. When chilled castings are to be 
made, iron for chilling purposes must be introduced in the 
flask either as part of the flask itself as in the case of car 
wheels (Fig. 3) or placed in a pocket in the mold the same as 
a core. This latter method requires a print on the pattern 
to form a pocket for the chill. The amount of iron in the 
chill should be two or three times as great as in the 
portion to be chilled and the pattern-maker must arrange 
his pattern accordingly. 



CHAPTER VIII 

CORE PRINTS 

41. Core Prints. A core print is a projection on a pattern 
or core-box for making an impression to support a core. 
The cores placed in the impressions thus made are usually 
composed of a mixture of coarse clayless sand and a bind- 
ing material, which when baked gives a hard core. As the 
moisture is dried out of the sand by baking, they are called 
dry sand cores. If a separate piece like a core is to be 
introduced in a mold, there must be an impression in the 
sand which will locate and support it. This is the office 
of the core print, which for easy and accurate location 
is usually attached to or made a part of the pattern itself. 
When the reversal of a core in a mold would spoil a casting, 
the core prints must be made of such shape and size that 
the molder would find it impossible to set the core in any 
position except the proper one. \ 

In Fig. 55, it will be noticed that the tapered print is 
made loose, for the molder wishes to lay the pattern on the 
mold board with the flat surface, on which this print is 
located, down, and any permanent projection would be 
in the way. When the pattern is rammed up and the drag 
rolled over, the broad surface is uppermost and is to be 
covered with the cope. The tapered print will thus be en- 
tirely in the cope and for this reason the tapered or loose 
print is often called the cope print. The angle of taper 

as 



66 



PATTERN-MAKING 



is made comparatively large in order to steady the core 
when closing on the cope. There is no standard for this 
angle, but an angle of 15° with the axis, making 30° included 
angle, is easy to lay out, is satisfactory in use, and might 
well be adopted as a standard. 

Prints for horizontal core 



Parting 



Line 




cope print" 



Parting 



' ] 1 ' 1 1 1 1 1 1 1 1 1 1 1 1 'I ' I"! ll-V l-l-l 1 1 1 | 1 1 1 | 1 1 

Pattern 


Line 










drag print 







Fig. 55. — Simple Core Prints. 



The drag or nowel print is nearly straight and has only 
enough draft to allow it to part from the sand readily. 
This print is so nearly straight that it is often called the 
straight print. As its presence does not interfere with the 
molder's operation, it is usually fastened to or made integral 
with the pattern proper. 



CORE PRINTS 



67 



The length of these prints should be only enough to 
furnish sufficient bearing in the sand so the weight of the 
core will not tend to crush the mold. When the core is 
supported at both ends, it is not necessary for the length 
to equal the diameter even in the smallest sizes, and as the 
diameter of the core increases, the proportionate length 
decreases until we have a length of about six inches for a 
core fifteen inches in diameter. 

Prints for round cores can be turned with a dowel which 
locates the print accurately on the pattern whether the 

Better method insuring correct 
placing of core 




Fig. 56. — Pipe Ornament Pattern. 



print is to be loose or solid. By adopting a standard size 
of dowel, it is possible to use a wide variety of print sizes 
on the same pattern. One of the common uses of cores 
is to cause holes in the hubs of gears or pulleys which are 
to be bored out to fit different sizes of shafts. For this 
purpose, different core prints may be used on the same 
pattern, thus getting a variation in the size of hole, and if 
the size of the hub will not allow enough range in the size 
of the hole, the pattern may have interchangeable hubs. 

When the core is supported at one end only, and espe- 
cially if it lies horizontally in the mold, the core must be 
made long enough so that the part resting on the sand will 



68 



PATTERN-MAKING 



more than balance the unsupported portion. (Fig. 56.) 
To bring this about, the prints for such cores have to be 
made longer or of a greater section than is the case where 
the crushing effect is the only point to be considered, and 
such patterns are said to be made for a balanced core. 
When a core is to be located in a portion of the mold 
that is below the parting line, the print must not only form 




Drop or 
heel core 



Cope side 



Line 




Print 



Print 



Fig. 57. — Drop or Heel Prints. 



a pocket for the core to rest in, but it must also make an 
opening in the sand through which the core may be passed 
to its proper place. (Fig. 57.) These are called drop or 
heel prints. 

For all these reasons, the core print attached to a pat- 
tern very often does not convey any idea as to the shape of 
that part of the core which actually causes the hole in a 



CORE PRINTS 



69 



casting, and consequently work involving cores and core 
prints calls for a great effort of the imagination on the part 
of the pattern-maker and makes it one of the most difficult 
branches of the trade. 

42. Loose Pieces. Patterns sometimes have project- 
ing portions which are made separately and fastened to the 
pattern by skewers or pins; they are not for the purpose 
of making a supporting pocket for a core, but are to be 



Cope side 



Fartin g 



line 



Heel print 


\ 




/ 










Loose boss 






V f 








/ 




\ 


r~ 










Loose 
print 






1 


Loose boss 












r 










1 



Fig. 58. — Loose Pieces. 



reproduced in metal. (Fig. 58.) These loose pieces, 
as they are called, are often preferable to cores, even where 
cores might be used to " core on " the part, as they avoid 
scars on the castings and thus leave smoother surfaces. 
This method is also used in some cases to avoid making 
a split pattern. If a certain surface must be cast in the 
drag in order to produce a sound casting, it may happen 
that one slight projection will not allow the pattern to be 



70 PATTERN-MAKING 

drawn. If this projection can be made loose, so that the 
pattern can be drawn, then the loose piece may be " picked 
in " or drawn into the cavity left by the main pattern, 
and we can accomplish the result desired with but little 
extra work for the molder. This loose piece may be held 
in its place on the pattern by skewers or pins, or be dove- 
tailed into the pattern to give support until the sand has 
been rammed around it. Then the pins may be withdrawn 
and the ramming completed, leaving the loose piece to be 
picked in after the pattern proper has been drawn. 



CHAPTER IX 
CONSTRUCTION OF PATTERNS 

If pattern-making is one step in the process of secur- 
ing a certain number of satisfactory castings at the lowest 
possible cost, it will be seen at once that the method of 
making the pattern must be governed by considerations 
other than those which would produce the cheapest pattern. 
Cheap castings and not cheap patterns is the goal to be 
reached. Bearing in mind the two cardinal virtues of 
pattern-making, (1) strength and durability, and (2) per- 
manence of form, the different methods of construction 
which may be employed can now be considered. The choice 
between methods is governed by questions relating to opera- 
tions outside of the pattern shop. The pattern-maker, 
having decided on the type of pattern, should make his 
pattern with the least possible expenditure of time and 
materials. 

43. Methods of Construction. Advantages of Each. As 
a rule the amount of lathe work as compared with bench 
work is small. The methods employed by the wood turner 
produce work of fine appearance but such work will not 
stand the tests demanded by the accuracy of pattern-making. 
This accounts for the scraping done by the pattern-maker 
which is much slower but at the same time more accurate 
than the cutting which is used almost exclusively in wood 
turning. The appearance of a scraped surface before sand- 

71 



72 PATTERN-MAKING 

papering is not as good as that of one which has been cut 
but its accuracy is usually greater. 

As distortion and liability to fracture are largely due 
to moisture on the one hand and to rough usage on the other 
hand, both must be carefully guarded against. Moisture 

Strips sawed 




Fig. 59. — Method of Gluing up to Decrease Warping Effect 

may be kept out by constructing the pattern in such a way 
that the least possible amount of end grain is exposed and 
by thoroughly protecting the surface of the finished pattern 
with shellac. 

Strength is imparted by building up the pattern in 
sections with the grain running in the direction of the great- 



CONSTRUCTION OF PATTERNS 



73 



est length of the different parts, and by making the joints 
overlap one another so that fracture must take place across 
the grain of the wood and not through a glued joint. 

Stock for thin work should be cut into strips, every 
other strip turned end for end and turned over. (Fig. 
59.) This reduces the tendency of the pattern to warp. 
Do not cross-glue pieces as the edges will not stay in shape 
and this would be particularly bad on the draw side of a 



Cope Side 



Parting 




Line 



Fig. 60.— Plain Molding Joint. 



pattern. End grain should be sized before gluing up, 
and all glued joints should be rubbed as much as possible. 
44. Classes of Patterns. Patterns may be made com- 
plete, sectional, or as skeletons to be used in connection 
with a strike. If the parting between cope and drag is 
perfectly plain (Fig. 60), the molder has less work, and 
naturally he prefers patterns with plain partings. If the 
molder's joint does not coincide with that of the pattern- 
maker (Fig. 61), more time must be spent in the foundry 
and the pattern-maker must justify this increased cost 



74 



PATTERN-MAKING 



by decreased cost of his pattern, viewed in the light of the 
number of castings required. Another class of patterns is 




Fig. 61. — Irregular Molding Joint. 

made to be used in connection with a multiple-part flask. 
(Fig. 62.) This often saves heavy and expensive cores and 
core-boxes, although calling for special flasks. 




Fig. 62. — Cam Pattern to be Molded in Three-part Flask. 



45. Small Patterns. Small patterns which have a short 
draw are often made with very little draft and practically 



CONSTRUCTION OF PATTERNS 75 

no allowance for shrinkage, as the rapping will allow the 
pattern to be drawn and will also increase the size of the 
mold enough to allow for the shrinkage of the metal. As 
the depth of draw is increased, the amount of draft must 
be greater as the rapping will not open out the sand as much 
as is the case with a short draw. When the drag is very 






Fig. 63. — Halved or Checked Spokes for Six Spoked Spider. 

deep, the pressure of the metal will often enlarge the mold 
as much as, or more than, the allowance usually given for 
shrinkage, and this fact must be considered by the pattern- 
maker. 

Draft on the inside of a pattern, especially when the 
body of sand is small, must be greater than on the outside. 
For small circular green sand cores, such as are used for 
bolt holes, the use of a tapered burning iron is recommended 



76 PATTERN-MAKING 

as a satisfactory and rapid method of obtaining the proper 
taper for draft. 

46. Built-up Patterns. In building up patterns which 
require spokes, such as gears, pulleys, etc., the arms may 
be halved or checked together (Fig. 63), or they may be 
joined by butt joints (Fig. 64). The latter method, espe- 
cially if reinforced by a feather in each joint or by what is 
know^i as Canadian dovetailing, involves less hand work 
and is sufficiently strong in most cases. The hubs used 




Fig. 64.— Five Spoked Spider with Butted Joints. 

on this class of work are let in slightly and strengthen 
the joint. If no hubs are required, a thin piece of hard 
wood or metal may be let in flush. 

The Canadian dovetail just referred to is not a true 
dovetail, but is like the locked corner joint seen on small 
boxes. (Fig. 65.) An ordinary circular saw with an 
attachment for moving the ripping fence the width of a 
groove and a tongue, or with a narrow guide the thickness 
of the saw located permanently parallel with the saw and 
the thickness of the tongue to one side of it, will do this 
work and will prove a good investment in any pattern shop. 



CONSTRUCTION OF PATTERNS 77 

Outside corners on built-up work if left sharp should 
be mitered to conceal end grain and reinforced on the inside 
with a square strip glued or screwed into the corner. If 
the corners are to be rounded slightly, a butt joint may be 
used. When the rounded corner is of large radius, and espe- 
cially if it is liable to injury, the sides may be rabbeted 
into a hard wood corner, thus concealing the end grain, 
reinforcing the corner, and giving the curve in the hard 
wood. (Fig. 66.) 




Fig. 65. — Canadian Dovetail. 

Turned split patterns may be held while turning by 
pinch dogs, corrugated fasteners or by thin steel rings beveled 
on the inside and driven in flush. The last method is free 
from danger caused by flying pieces, but does not permit 
the pattern to be opened during construction as is sometimes 
desired. 

As screws do not hold well in end grain, a plug of hard 
wood if desired, may be placed across the grain so that 
the screw may pass through it. If the screw is to be removed 
many times it is better not to glue the plug in, so that it 



78 



PATTERN-MAKING 



may be renewed. (Fig. 67.) When a perfectly smooth 
surface is desired, especially on the draw side of a pattern, 




Fig. 66. — Hard Wood Corner. 




Fig. 67. — Screws in End Grains. 

screws may be concealed by first counterboring so that the 
heads may be sunk below the surface, and then gluing 
in wooden plugs which may be worked off flush. 



CONSTRUCTION OF PATTERNS 79 

47. Circular Work. Flat circular work, especially that 
in the form of rings, should, for permanent construction, 
be laid up in segments in which the grain runs the longest 
way. The greater the number of segments in each course, 
the more nearly the grain follows the circular form and the 
less the amount of end grain exposed. The number of 
segments used is usually 4, 6, 8, 9, 12, or 18. The joint 
between adjacent segments may be the butt, feathered 
or keyed, or, best of all, the Canadian dovetail. The larger 
the surface for gluing and the stronger the mechanical 




Fig. 68.— Dovetail Plates. 

construction, the greater the permanence of the course. 
As the courses are glued one upon another, care should be 
taken to break joints. A single course of segments may 
be reinforced by dovetail plates of hard wood or metal let 
in as shown in Fig. 68. When the Canadian dovetail 
is used, this is hardly necessary. When the courses are 
quite thin, shoe pegs may be driven through, thus rein- 
forcing the glue. A ring may be jointed up in one thick 
course, the joints fastened with the Canadian dovetail, 
and then sawed into a number of thin rings which may be 
glued together, breaking joints, thus saving time over what 
would be needed to handle a large number of small pieces. 



80 PATTERN-MAKING 

If a circular pattern is so deep that the inside cannot 
be turned easily when completely built-up, such as a pattern 
for a bell, a few courses may be laid up, turned on the inside 
to a templet, a few more courses applied, turned as before, 
and so on until the inside of the pattern is finished. 

48. Large Patterns. Large circular work such as cylin- 
ders, columns, etc., are usually made by placing long strips 
or staves on an interior braced form. (Fig. 69.) A sur- 
face made in this manner is called lagging. The flanges 
are often turned separately and fastened in very securely 




Fig. 69. — Staves Assembled for Turning. 

as they are harder to draw and so get more rapping. As 
patterns of this kind are apt to be long in the sand, they are 
likely to swell. To avoid buckling, the staves are often 
laid with open joints. This form of construction is fol- 
lowed in patterns for large flat plates, also in large webs, 
or in any place where swelling would be likely to distort 
the pattern. 

The same idea of an interior braced form as used for 
lagged work is employed in any large pattern when the 
drawing calls for no ribs or webs which would hold together 



CONSTRUCTION OF PATTERNS 



81 



the flat sides of the pattern. Due to the box-like structure, 
such patterns are called boxed-up. 

Different lengths of castings may be made from the 
same pattern by stopping off the mold. Such castings as 
engine beds, lathe beds, cylinders, and columns are made 
in this way with a comparatively small expenditure for 
patterns. (Fig. 70.) The stop-off pieces must suit the 
shape being made. 



To be filled 
with sand 




Fig. 70.— Mold with Stop-off Piece in Position. 



49. Helical Forms. Patterns for screw propellers are 

made in various ways; a complete pattern with hub and 
blades, a hub with one blade, or a hub and one separate 
blade. When made in connection with the hub, the blade 
is usually laid up as shown in Fig. 71. The face of the blade 
is then worked off to a true helix using the joint lines as 
guides. To obtain the thickness of the blade, plugs as 
long as the thickness of the blade may be driven in at various 
points, and the back of the blade may then be worked off 
until flush with the ends of the plugs. 



82 



PATTERN-MAKING 



Another instance of the use of the helical form in pattern 
work is in a worm for a worm gear. It could be molded 




Fig. 71.— Propeller Blade Pattern Assembled. 

horizontally, using a split pattern, but this method would 
probably leave a fin at the parting of the flask which would 



CONSTRUCTION OF PATTERNS 83 

interfere with its use unless machined carefully. To get 
a clean casting without a fin, a solid pattern may be used, 
molded on end in a deep flask, and drawn by turning and 
lifting at the same time, the proper relation between them 
being determined by a special rigging carrying a thread 
of the same lead. 

50. Match Work. When many castings are to be made 
at once in a flask, or when a large number of single castings 
of irregular parting line are required, the placing of the 
patterns, cutting the gates and runners, and cutting irregular 
partings may be avoided by using the pattern on a follow 
board or on a plate called a match. The match may be 
made first, the pattern built upon it and patterns of the 
gates and runners placed in position and fastened to the 
pattern. If the cope side of the pattern is irregular, this 
match or follow board may be made of plaster of Paris 
so that the cope portion of the pattern may be imbedded 
in the plaster up to the parting line. 

In the match work just referred to, the pattern is sep- 
arate from the board, which is removed when the cope is 
to be rammed. But patterns are frequently mounted 
permanently on a flat metal match plate thick enough to 
stand the ramming and with the cope and drag parts of the 
pattern located exactly opposite one another. On the 
drag side of the plate are placed patterns for the gates and 
runners. Holes in the plate to match the flask pins keep 
the plate and the two parts of the flask in proper relation. 
When the ramming is completed the cope and plate are 
lifted from the drag and then the plate is lifted from the 
capsized cope. There is a tendency in the foundry practice 
of to-day to make the cope and drag of a mold on separate 
machines. This means that, instead of a single plate with 
the patterns matched on opposite sides, there are two plates, 



84 



PATTERN-MAKING 



one with the cope part and one with the drag part of the 
pattern so located that when the copes and drags which 
are made on different machines are assembled, perfect 
molds will result. 

51. Spur Gear Patterns. When making patterns for 
spur gears with cast teeth, there are several different methods 
for getting out the teeth for the pattern: (1) If the gear 
is small in diameter and without spokes, the pattern may 
be turned from one piece with the grain running in the 
direction of the tooth. After carefully laying out the whole 




Fig. 72. — Five Methods of Attaching Teeth to Rim of Gear Pattern. 



gear, the teeth can be worked from the solid. (2) In larger 
gears the spider may be mortised into a segmental rim the 
root diameter of the gear, and blocks glued on with the grain 
running across the rim. After carefully facing the ends 
of the blocks and turning to the outside diameter, the teeth 
may be laid out and worked in place. (3) With a rim of 
root diameter, a block for each tooth is fastened to the 
rim by a slightly tapering dovetail. After turning and lay- 
ing out, the blocks are removed, worked to shape and re- 
placed. (4) Blocks are worked out to shape independently 
in a jig, screwed to a rim of root diameter on which properly 
spaced lines have been carefully laid out, and the screw 



CONSTRUCTION OF PATTERNS 85 

holes plugged. The molder finds it of great advantage when 
finishing up a mold of a gear to have two or three separate 
teeth which he may remove from the pattern or which 
may be made for the purpose. Cherry teeth on a pine 
rim make an excellent gear pattern. 

The methods of laying out gear tooth outlines vary all 
the way from free hand sketching to the use of zinc templets 




Fig. 73. — Jig for Working Out Teeth for Spur Gear Pattern. 

which have been laid out mathematically. Between these, 
and accurate enough for all practical purposes, is the use 
of the Grant or Willis odontograph, a simple and universal 
templet, the use of which is explained in the maker's 
circulars. 

.52. Bevel Gears. Making patterns for bevel gears 
is more difficult, as all lines are elements of cones instead 



86 



PATTERN-MAKING 



of elements of cylinders. This makes nearly impossible 
any method of tooth formation which uses a surface below 
the root surface. If teeth are worked out by hand, they 
may be laid out to the proper shape at each end and then 
worked from line to line, or they may be made in a jig. 
The band saw is a most useful tool in getting out either 



Spherical 
guide 



Fig. 74. — Method of Band Sawing Teeth on Bevel Gear Pattern. 



spur or bevel teeth. For spur gears, the tooth must be 
held parallel to the saw all the time, so the flat table itself 
is the only guide needed. Bevel teeth require a spherical 
guide, the diameter of the inner end of the teeth, with the 
cutting edge of the saw passing radial to the sphere. (Fig. 
74.) The outer end of each tooth is laid out and the 
gear carried on a concave holder so that any radius of the 



CONSTRUCTION OF PATTERNS 87 

sphere would pass through the center of the tooth, on the 
pitch circle. Teeth sawed in this way should require no 
finishing except with sandpaper. 

53. Branched Patterns. Patterns having branches, espe- 
cially if either the body or the branch is of curved section, 
are somewhat difficult to lay out. A full size development 
on paper can be cut out, folded around the branch, and used 
as a marking templet to show where the branch must be 
cut to fit the body. (Fig. 75.) Another method is to 
hold the branch at the proper angle on a form which has 



Fig. 75.— Half Branch Coped On. 

on it a plan of the pattern, and use a band saw to cut to 
the outline of this plan, thus giving the proper shape to 
fit closely to the body. Both these methods are called 
coping-on. A branch may be let into the body either wholly 
or in part. It is not often that the band saw can be used 
in this method, the folded development serving better for 
laying out and the letting-in is accomplished by the use of 
hand tools. 

54. Marking and Numbering. During the process of 
shellacking is the time to apply letters and figures, either 



88 PATTERN-MAKING 

for purposes of identification or for inscriptions. They 
are usually placed on green shellac and fastened with brads, 
although screws are better if they can be used. For pur- 
poses of identification, a thin aluminum plate with raised 
figures and letters is preferable to separate characters. 
Separate, figures are small, are not easily fastened, and the 
loss of one might give an entirely wrong number to the 
casting. The pattern and everything belonging to it, 
core-boxes, loose prints, loose pieces, etc., should carry 
the same pattern number and a figure representing the 
number of separate pieces in the group. This last figure 
is especially serviceable when shipping the pattern from the 
shop to the foundry or vice versa. 

55. Fillets. Fillets are also applied at this time. Wax 
and putty fillets should be applied with a fillet tool after 
the first coat of shellac. Wood and leather fillets are shel- 
lacked on the back, laid in green shellac, and rubbed into 
place with a fillet tool of proper radius. Lead fillets usually 
rely on brads to hold them in place, but all fillets have 
one or more coats of shellac over them. 

56. Shellacking. Shellac should be applied in several 
thin coats, each allowed to harden and then rubbed 
down with old or dull sandpaper, the only instance where 
a dull tool is better than a sharp one. The last coat 
should be left right from the brush and not rubbed down. 
The practice of burning off to hasten drying is only excusable 
when the order reads " Cast this yesterday." End grain 
being porous will absorb shellac so fast at first that an extra 
coat to seal the pores is often applied. This is about the 
same as sizing before gluing. Orange shellac is transparent 
and will not conceal poor workmanship; it also inspires 
the molder with greater respect for the patterns as the results 
of abuse are more easily seen. For these reasons many 



CONSTRUCTION OF PATTERNS 89 

concerns use light colored patterns exclusively, with differ- 
ent colors for the parts which need to be distinguished. 

57. Weight of Castings. The weight of castings may 
be estimated quite accurately from cubic measurement 
of the casting part of the pattern or approximately from the 
weight of solid patterns. When calculating by cubic 
measurement, allow .26 pound for every cubic inch of cast- 
iron and .30 pound in case the metal is brass. If solid 
patterns are of pine, the weights of castings in cast-iron 
or brass will be approximately 16 to 1 or 18.5 to 1 respect- 
ively. Another method applicable to any material used 
for patterns is to take the weight of 3.85 cubic inches of the 
material used for the pattern in case the casting is to be in 
iron, or of 3.33 cubic inches if it is to be in brass. Then 
the weight of the pattern divided by the weight of this 
test block will be the weight of the casting. In using any 
of these methods, core prints and other parts not repro- 
duced in metal should be deducted. 



CHAPTER X 

I 

CORE-BOXES AND CORES 

58. Cores. A core is something projecting into the mold 
cavity so as to cause a hole in the casting. 

It may be a body of molding sand formed by a tapered 
recess in the pattern. As this is part of the mold itself 
and made of sand which has had no preparation other than 
tempering, it is called a green sand core. It is the cheapest 
form, as it does not require the making of core-boxes in the 
pattern shop, or the making and setting of cores in the 
foundry. 

When a green sand core cannot be used, one of dry sand 
may be employed. This is made of a coarse sand free from 
clay, mixed to the consistency of a stiff dough with a bond 
having a base of sugar or starch, and baked until perfectly 
dry and hard. For fine work and especially for brass cast- 
ings, dry sand cores are often made of burned molding 
sand or of beach sand. The reason for using sand free from 
clay is that a clayey sand would bake too hard to be readily 
shaken out of the casting. The core, while it must resist 
the flow and pressure of the molten metal, must crush under 
the shrinkage strain of the metal in order to avoid cracking 
the casting, and must break up easily so that it can be 
taken out. 

Sometimes cores are made of metal, usually wrought 
iron or steel, in order to leave a surface so smooth and 
accurate that no machining is necessary. In this case, of 

90 



CORE-BOXES AND CORES 91 

course, the core is not destroyed, but is made slightly 
tapering so it can be removed from the casting. Such 
cores are usually used in brass castings, as the chilling 
effect of such a core on cast-iron would leave the surface 
very hard and brittle. 

With green sand and metal cores, the pattern-maker 
has no concern beyond the effect these cores may have on 
the shape of the pattern itself. Dry sand core work, on 
the other hand, calls for a lively imagination and is probably 
the most intricate as well as the most important part of 
pattern-making. 

59. Core-boxes. After the shape of the core with its 
supports has been determined by the layout, the pattern- 
maker must turn molder, for he has to construct a mold 
of wood in which the core can be made. This is called a 
core-box, and goes to the foundry with the pattern. 

60. Supporting Cores while Baking. When the core 
is first made it is so soft that it may change shape from 
its own weight or from careless handling. It is necessary, 
therefore, for the pattern-maker to consider the way that 
the core can best be supported while baking. The simplest 
form of core is one which has a comparatively broad flat 
portion on which it can rest. If a core is circular in sec- 
tion, it may be stood on end to bake, or, if the length is 
great as compared with the base, it may be rolled out of 
the core-box onto some loose dry sand. 

A half core-box gives a flat support while baking, and is 
used on cores of various shapes to save expense in the pat- 
tern shop, or to obtain a support for baking. The foundry- 
man often does not like them, for it takes more time to 
make two half cores, and besides the parts must be pasted 
together to make a complete core. Many cores which 
could not be baked safely on a flat plate, may be supported 



92 PATTERN-MAKING 

on a bed of green sand, to hold which the pattern-maker 
may make a rough frame. The core.-maker prefers this 
method rather than the use of a part box. 

When cores are very intricate, the question of support 
is extremely important. In such cases it is often desirable 
to make a cast-iron dryer of such form that the core is sup- 
ported at every point and all curved portions have intimate 
contact with the dryer. This means extra work for the 
pattern-maker and work for which he has no drawing. 
It should only be undertaken after consultation with the 
foundry foreman. 

61. Large Cores. Large cylindrical cores which would 
require a large and expensive core-box, would use up a very 
large amount of core sand, and which would be very heavy 
if made in this way, are usually made on a cast-iron core 
barrel and are called loam cores. The barrel is first wound 
with hay rope and the loam mixture is applied in a softer 
state than dry sand and smoothed off with a strickle. As 
the barrel is being turned during these operations, the 
core is circular in sections at all points, and takes the form 
determined by the strickle. These cores are held by the 
shaft of the barrel and baked as are those of dry sand. 
Both large dry sand and loam cores are black-washed. 
after baking. This consists in applying carbon, usually 
in the form of graphite, to the surface of the core. The 
carbon prevents the core sand from burning to the casting 
and aids in making the core part easily from the surface. 

62. Classes of Cores. Thus it will be seen that with 
regard to construction, cores may be divided into four classes : 
(1) complete cores which lie as they are made, (2) cores 
which are turned over, (3) complete cores supported 
on sand or cast-iron dryers, (4) barrel or loam cores 
which require no boxes. t 



CORE-BOXES AND CORES 



93 



63. Placing Cores in the Mold. Dry sand cores are 
placed in the mold accurately by the guiding effect of pockets 
in the sand made by the core prints on the pattern. It 
is evident that the cores must fit closely, yet if they are at 
all over size the core will have a tendency to crush the 
mold. As cores are apt to swell somewhat in baking, 
they must, especially in large sizes, be made in boxes which 
are somewhat smaller than the finished core. Making the 
pattern by the shrink rule and the core-box by the standard 
rule usually gives sufficient allowance, but in small work 
where the difference between shrink and standard measure- 




Fig. 76. — Fillet on Core Print next to Casting Part of Pattern. 



ments is small, both may be made by the shrink rule, as 
the effect of rapping, which makes the mold larger and the 
core smaller, gives the leeway necessary. 

If the mold is left sharp where the core pocket joins 
the mold proper, crushing is apt to take place even with 
light cores. A fillet on the pattern at this point or a taper 
at the base of the core print (Fig. 76) which is not repro- 
duced in the core, will serve to prevent sand being dislodged 
to fall into the mold. 

64. Construction of Core-boxes. Core-boxes for small 
standard cores should be made of metal carefully finished 



94 



PATTERN-MAKING 



for. which special patterns, often of plaster of Paris, must 
be provided. Ordinarily, core-boxes are made of wood. 
The working part of the box consists of the outline of the 
core with the proper section, a finished face which comes 
in contact with the plate or with the dryer, and a bottom 
either solid or skeleton which brings the face of the box 
horizontal when in the ramming position. The bottom and 




Fig. 77. — Two Parts to be Pasted together to Form Half Core 
for Globe Valve Body. 



sides are not shellacked or even finished. These boxes 
must be fastened together very securely, as the core-maker 
uses a mallet quite freely on the bottom and sides to free 
the core before lifting the box. This accounts for a greater 
use of screws in the construction of core-boxes than is usual 
in patterns. Core-boxes are often made with core prints 
in them to make impressions to receive other cores (Fig. 



CORE-BOXES AND CORES 



95 



77), or with loose pieces which are sometimes arranged to 
be drawn before the box is lifted; in other cases, they are 
designed^o-be drawn after the core is on the dryer. 

In order to avoid working out to any great depth in a 
solid block by the use of hand tools, it is customary for 
cores of varying section to assemble as many pieces of 
wood as there are changes in section, together with a bottom 




Fig. 78. — Parts for Half Core-box for Pipe Fitting Assembled 
and Laid Out. 



or back which keeps all the pieces in proper relation. The 
workman can then finish the face, lay out reference lines 
upon it (Fig. 78), take down the box, lay out each individual 
piece from the reference lines, work each out by the easiest 
method, reassemble the box, apply fillets, etc., and shellac 
the box proper and the face. There is more hand work 
on core-boxes than is the case on patterns, as most of the 



96 



PATTEKN-MAKING 



circular sections would involve inside turning. The gouge 
takes the place of the lathe in many cases, although the 
core -box machine, which is really a device for inside turn- 
ing, may be used over a wide range of sizes. 

65. Placing Large Cores. Large cores which are set 
flat in the mold can be placed by measurement and not 
located by core prints. These- are often called lightening 




o 



Fig. 79. — Half Core-box Showing Core Carrying Wrought Iron 
Flush Handle. 



cores, making the casting, much thinner as in the case of 
machine tool bases. 

A core may be made to furnish the pocket and to carry 
the stock for a flush handle or similar work. (Fig. 79.) 

66. Surfaces. A surface to be pierced with holes may 
have small green sand cores if the surface is flat, but if the 
surface is curved so that green sand cores cannot be formed, 
small dry sand cores the thickness of the metal may be 
fastened to the drag surface by nails. In the case of a 



CORE-BOXES AND GORES 



97 



cylindrical strainer closed at one end these nail cores may 
be set on the body core and also act as chaplets to support 
the overhang. (Fig. 80.) In many .cases a series of holes 
may be bored through the pattern and a plug turned to the 
same diameter may be forced through the pattern into the 
sand to make impressions for dry sand cores. Fixed 
pattern letters on the draw side of a pattern would interfere 




\ i \ \ \ r/ \ / 

o i ! lijl ! I o 



■ 



Fig. 80.— Multiple Core-box for Nail Cores. 



with molding. A print including the same area might be 
picked in and a core set bearing a mold of the letters re- 
quired. These name plate cores require that the pattern 
letters appear in the core-box and not on the pattern. 

67. Covering Cores. These are often used, not to make 
a hole in the casting, but to avoid the use of a three-part 
flask. As an illustration of this take the case of the casting 
shown in Fig. 81. The pattern is laid on face a, the drag 



98 



PATTERN-MAKING 



rammed to joint b, the other part of the pattern placed, 
and rammed to line c, tucking the sand well under the 
flange. Then part 1 of the pattern is drawn and a cover 
core placed in the pocket made for it by the cover core 



1 Cover core print 



Section of pattern 







I 



Fig. 81. — Section of Two-part Mold Showing Cover Core Mak- 
ing Three-part Flask Unnecessary. 



print. The ramming of the drag can then be finished and, 
after making a plain cope, part 2 of the pattern can be 
drawn. This method can also be used in many cases where 
it is imperative that certain surfaces be molded in the drag 
as in the case of bearings on pedestals and machine bases. 



CORE-BOXES AND CORES 



99 



In the case of a double shrouded gear, a ring covering core 
for the lower shroud would avoid casting the teeth in cores 
or in a three-part flask, and give a smoother job. 

68. Ring Cores. The use of a three-part flask may also 
be avoided by the use of a ring core. If the diameter is 
large, they are usually made in sections to reduce the cost 
of the core-box and to insure greater safety in handling the 
core. Good examples of this work are cable sheaves and 
chain wheels. A section of one is shown in Fig. 82. 



;->v^s 




Fig. 82. — Mold for Sheave Showing Ring Core. 



69. Hollow Cores. Sometimes a pattern could be drawn 
easily if it were not for some slight proj ection. As has already 
been pointed out, if the small piece can be drawn into the 
main cavity, it may be attached to the pattern as a loose 
piece. If it cannot be so drawn, a hollow core may be 
used, the interior of which is a mold for the part in question, 
the print for this core being of such a shape that it can be 
drawn with the pattern. (Fig. 83.) 

70. Castings without Patterns. If part of a casting 
can be made in a core, it is but a step to make a casting 
without any pattern at all, using core-boxes only. This 
is usually done only on large work, the cores in some cases 
being so large and heavy that it pays to make them in 



100 



PATTERN-MAKING 



sections and stack them. Among the smaller class of cast- 
ings which are sometimes made in this way may be noted 
cast chain, only one core-box being needed. (Fig. 84.) 

Round flasks with their trunnions for lifting and roll- 
ing can be cast in cores, also columns with their bases, 
I 

. Cope side 



parting 



line 




Fig. 83.— Part of Mold Showing Hollow Core for Casting 
on a Handle. 



caps, and brackets. Large fly-wheels can be cast in cores 
by sweeping the depth of the rim to the outer diameter 
and using a core for the center, one for each arm, and a 
covering core for the rim and for the hub. 



CORE-BOXES AND CORES 



101 




CHAPTER XI 

SKELETON PATTERNS AND SWEEPS 

71. Skeleton Patterns. Skeleton patterns and core- 
boxes are used for several reasons; as they take less stock 
and time, they are cheaper to build, and as they are much 




Fig. 85. — Skeleton Core-box with Strike. 

lighter, they are easier to handle in the foundry. As the 
sand surfaces are made by the use of strikes, the pattern 
merely serving as a guide, the actual molding operations 
may take more time, but this is more than offset by the 
saving in the pattern shop. 

Large cores can often be formed directly on the plate 
by the use of a skeleton box and strikes. (Fig. 85.) In 
the case of some simple forms, nothing is required but a 
core board to give the general direction and a single strike 
to give the proper section. (Fig. 86.) A skeleton pattern 

102 



SKELETON PATTERNS AND SWEEPS 



103 



may be made of any outline, no 'matter how irregular, 
provided the strikes can follow that outline. 

72. Sweeping. When the main portion of a mold is 
circular in section, a strike swung in a circular path will 
produce the form desired. In such a case, the guiding 
effect may be obtained without the use of any pattern. 
A rigid vertical spindle can be erected in the foundry 
floor and the strike fixed so as to revolve around it. This 
method is known as sweeping and strikes used in this 




Fig. 86.— Core Board with Strike. 



manner are usually called sweeps. Swept-up molds 
are not usually made in flasks, but on a level plate con- 
centric with the spindle. A form of bricks is laid up in mud 
with wisps of straw between the bricks to vent the 
mold, to within about an inch of the first or roughing sweep, 
and loam is built upon this form until the sweep strikes 
every portion of it. (Fig. 87.) A second sweep, allowing 
a finishing coat of loam about a half an inch in thickness, 
may then be used. These inside sweeps may be held at 
top and bottom and should have the thickness of the metal 
indicated upon them. 

The loam mixture consists of fire sand and molding sand 



104 



PATTERN-MAKING 



mixed with clay water. Some chopped straw is mixed 
with it to make the mixture more porous. As it is applied 
with a trowel, the consistency should be about the same 
as that of a stiff mortar. 

The cores for loam molds are formed the same as the 
molds themselves, but the sweeps cannot be supported at 



o 




Fig. 87. — Sweep for Outside of Casting. 



the bottom, making it necessary to give particular atten- 
tion to the top support. These are called outside sweeps 
as the loam is placed on the outside of the brick form. (Fig. 
88.) 

The mold and core are swept up on separate plates, 
dried out, black-washed, and, if the mold is a large one, 
placed in a pit in the foundry floor, and sand filled ill around 



SKELETON PATTERNS AND SWEEPS 



105 



it to resist the pressure of the metal. A smaller mold might 
be held by chains. 

A large pipe with nozzles may have the pipe proper 
swept up and part patterns used for the nozzles. These 
nozzle patterns can have cover core prints for the flanges, 



MOl 



EZ 



G 



j^ 



a 



r© 



v> 



t 

^ of Casting 

| Strike 



Spindle- 



V 

Fig. 88. — Sweep for Core or Inside of Casting. 

and a large cover or slab core can be used for the face of 
the upper flange of the pipe. Loam molds may also 
be made by the use of skeleton patterns and strikes, no 
spindle being employed. 

After a loam core has been made on a core plate, and 
dried, it may be black-washed and a sand thickness built 



106 PATTERN-MAKING 

upon it, using for a gage either a strike, thickness strips 
(the spaces to be filled in), or nails with a gage for depth. 
On this sand pattern, a loam cope may be built and dried 
in place. After lifting the loam cope the sand pattern can 
be removed. 

The blades of propellers may be swept up, using in con- 
nection with the spindle, an outside guide to give the 
pitch. In large sizes it is usual to have a separate cope for 
each blade. 

A grooved winding drum may be made in this way, the 
inside sweep having a guide to raise it uniformly during a 
full revolution an amount equal to the pitch. 



CHAPTER XII 

SPECIALIZATION IN THE PATTERN SHOP AND 
IN THE FOUNDRY 

73. Card Systems. The pattern shop must have a sys- 
tematic and convenient method of caring for the drawings 
from which its work is laid out. Probably a card system 
referring to the drawings (which should be kept flat in shallow 
drawers and never rolled) is the plan best adapted to shops 
of any considerable size. These cards could be divided 
into three classes: (1) drawings received but not issued, 
(2) drawings in the shop, and (3) drawings of completed 
patterns. The information finally recorded should include 
(1) the dates of receipt of drawing, commencement of work, 
and completion of pattern, (2) description of pattern with 
its identifying number, and a list of all core-boxes and 
special rigging, (3) names of workmen, their time and rate, 
(4) amount and cost of stock, (5) total cost of pattern. 
Many other items of value will suggest themselves in special 
cases. 

If the storage of patterns is placed in charge of the 
pattern shop, there should be a card index showing (1) 
patterns in storage, (2) patterns in foundry, and (3) patterns 
in shop for repairs or changes. Each card should show 
(1) date of receipt of pattern, (2) dates of issue, name of 
foundry, number of castings, and dates of return, (3) dates 
of transfer to pattern shop, memorandum of repairs or 
changes, and dates of return. 

107 



108 PATTERN-MAKING 

The keeping of these card systems should not be made a 
part of the duties of the shop foreman, but should be placed 
in charge of a competent clerk (although it might not take 
the whole of his time) who should be under the control of, 
and report to, the head of the pattern shop. 

74. Division of Labor. When a proper analysis shows 
exactly the work to be done in the pattern shop, then 
specialization may produce good results. The sub-divi- 
sion of hand labor has not yet reached the same degree in 
the pattern shop that it has in the foundry and the machine 
shop. This is accounted for in a large measure by the 
fact that a much smaller number of men are employed, 
yet it is not too much to suppose that in large shops there 
will be in the immediate future separate departments of 
laying out, getting out stock, construction, and finishing. 
The purely creative work of planning or laying out will 
be the most important and the best paid, the skilled work- 
man will find his opportunity in the construction depart- 
ment, while the getting out of stock and the finishing 
will fall to the lot of the workman of less ability and the 
apprentice. The time may come when each of these 
departments may be still further sub-divided. 

Efficiency in the use of a labor-saving machine consists 
in having the saving made by its use more than offset the 
interest on the investment, the depreciation of the machine, 
the cost of power to run it, and the probability that it may 
be superseded by a better one. This last contingency 
should be anticipated by a sinking fund. 

75. Relation of Methods to Foundry Practice. Speciali- 
zation in the foundry has reacted and will still further react 
on the pattern shop. The skilled molder who could handle 
successfully almost any form the pattern-maker chose to 
produce is being replaced to a great extent by the unskilled 



SPECIALIZATION IN THE PATTERN SHOP 109 

laborer. This has made necessary an arrangement of the 
pattern so that skill in molding is not required. The 
molding machine in its various forms is coming into general 
use for castings in lots as small as half a dozen. Follow 
boards are in greater demand, more patterns are being 
arranged for plate work, and all along the line there is a 
louder call for patterns which lend themselves to mold- 
ing by unskilled hands. 

One of the latest devices for saving labor in the foundry 
and one that reaches the hitherto untouched class of large 
castings, is the jar-ramming or jolting machine. While 
the use of this machine saves patterns from surface scars 
caused by hand or pneumatic rammers in the hands of 
careless molders, it puts a strain on the general construction 
of a pattern which was unknown in the old days. The 
effect of jolting a large pattern covered by a heavy body 
of sand tends to shake it apart, and calls for a stronger 
construction and for a more liberal use of screws than was 
considered necessary before the advent of this method. 

This tendency toward the use of unskilled labor in the 
foundry calls for a greater degree of skill in the pattern shop, 
especially in the planning department, and no pattern- 
maker, however great his skill in construction, can hope 
to qualify for the more important duty of planning unless 
he is acquainted with, and keeps himself fully abreast of, 
this rapid and fundamental change in modern foundry 
practice. 



INDEX 



Animal glue, 45 

Allowance for, draft, 15; driving, 

18; finish, 17; holding, 18; 

shrinkage, 13 
Arcs, Tools for large, 25 

Backing off, 42 

Balanced core, 68 

Band saw, 32 

Bars in cope, 7 

Bastard sawing, 44 

Bench, 20 

Bevel gear pattern, 85 

Bit, Forstner, 30 

Black wash, 92 

Blocks, V, 25 

Board, Bottom, 7; Core, 102; 

Follow, 57; Mold, 7; Pattern, 

7; Shoot, 26 
Boring machine, 33 
Bottom board, 7 
Boxed-up pattern, 81 
Brads, 47 

Branched pattern, 87 
Built-up pattern, 58, 76 
Buzz planer, 33 

Calipers, Marking, 30; Thickness, 

30 
Camber, 15 



Canadian dovetail, 76 

Casting, Chilled, 64; Original, 1; 
Weight of, 89 

Center, edge, 23; plates, 36; 
square, 23 

Chaplets, 8 

Cheeks, 6 

Cherry, 44 

Chill, 8 

Chilled castings, 64 

Choice of pattern, 10 

Chuck, Screw, 36 

Circular saw, 32 

Cold glue, 45 

Complete pattern, 73 

Cooling strains, 48 

Cope, 6; bars, 7; core print, 65; 
False, 8 

Coping, down, 56; on, 87; tram- 
mel, 25 

Core, Balanced, 68; Covering, 
97; Definition of, 90; dryer, 92; 
Dry sand, 59, 90; Green sand, 
59, 90; Hollow, 99; Lightening, 
96; Loam, 92; Metal, 90; Nail, 
97; Name plate, 97; Ring, 99 

Core-box, Construction of, 93; 
Definition of, 91; Half, 91; 
machine, 33; plane, 27; Skele- 
ton, 102 

1U 



112 



INDEX 



Core print, Cope, 65; Drag, 66; 

Drop, 68; Heel, 68; Length 

of, 67; Loose, 65; Nowel, 66; 

Straight, 66; Tapered, 65 
Cornering tool, 31 
Corners, Hardwood, 77; Round, 

31,48 
Corrugated fasteners, 36 
Covering core, 97 
Cradles, 25 
Cutters, Routing, 33 

Daniels' planer, 33 

Definition of, core, 90; core print, 
65; finish, 17; mold, 5; pattern, 
2, 15; pattern-making, 71 

Demand for pattern-maker, 2 

Disc grinder, 34 

Dogs, Pinch, 36, 46 

Double shrink, 21 

Dovetail, Canadian, 76; plates, 79 

Dowel plates, 48 

Dowels, 47 

Draft, 15 

Drag, 6; core print, 65 

Drawbacks, 6 

Drawing plates, 48 

Drawings, 1, 39; Caring for, 107 

Driving, Allowance for, 18 

Drop core print, 68 

Drop-outs, 7 

Dryer, Core, 92 

Dry sand, 6; core, 59, 90 

Edge center, 23 
End face plate, 35 

Face plate, 35, 36 
Facing sand, 7 
False cope, 8 
Fasteners, Corrugated, 36 



Fillet, 49; Lead, 50; Leather, 50; 

Putty, 50; tool, 49; Wax, 49, 

Wood, 49 
Finish, 17 
Fish glue, 45 
Flask, 6 

Flexible faced plane, 27 
Follow board, 57 
Form templet, 41 
Forstner bit, 30 

Gaggers, 7 

Gates, 8, 61 

Gear pattern, Bevel, 85; Spur, 84 

Glue, Animal, 45; Cold, 45; Fish, 

45; Hot, 45; Liquid, 45 
Green sand, 5; core, 59, 90 
Grinder, Disc, 34 
Guards, 37 
Gun, Wax, 50 

Hand jointer, 33 

Hardwood corner, 77 

Heel core print, 68 

Hexagon, Tool for laying out, 25 

Holding, Allowance for, 18 

Hollow core, 99 

Hook tool, 36 

Hot glue, 45 

Jar ramming, 109 
Jig saw, 32 
Jointer, Hand, 33 
Jolting, 109 

Knife, 22 

Lagging, 80 
Lathe, 35 

Laying out, hexagon, 25; large 
arcs, 25 



INDEX 



113 



Layouts, 38 

Lead fillet, 50 

Leather fillet, 50 

Letters, Pattern, 51 

Letting-in, 87 

Light, 37 

Lightening cores, 96 

Liquid glue, 45 

Loam, 6, 103; core, 92 

Loose, core print, 65 ; pieces, 69 

Machine, Boring, 33; Core-box, 
33; Jar ramming, 109; Mold- 
ing, 63 

Mahogany, 44 

Marking, calipers, 30; templet, 41 

Master pattern, 10 

Match, 8, 83; plate, 64, 83 

Materials, 43 

Metal, core, 90; pattern, 61 

Mold, board, 7; Definition of, 5 

Molding, machine, 63; sand, 5 

Nail core, 97 
Name plate core, 97 
Nowel, 6; core print, 66 
Nozzle, 105 

Odd-side, 8, 62 
One-casting pattern, 10 
One-piece pattern, 55 

Parting sand, 8 

Pattern, board, 7; Boxed up, 81; 
Branched, 87; Built up, 58, 
76; Choice of, 10; Complete, 
73; Definition of, 2, 15; letters, 
51; Master, 10; Metal, 61; One- 
casting, 10; One-piece, 55; Part, 
60; Propeller, 81, 106; Repair 



of, 10; Sand, 106; Sectional, 73; 
Skeleton, 71, 73, 102; Small, 
74; Split, 56; Spur Gear, 84; 
Standard, 10; Storage of, 107; 
Stove plate, 30, 57; Temporary, 
10; Thin, 30; Types of, 54; 
Winding drum, 106; Worm, 82 

Pattern-making, Definition of, 71 

Pattern-maker, Demand for, 2; 
Qualifications of, 3; Tools for, 
20 

Picking in, 70 

Pinch dogs, 36, 46 

Pine, 44 

Planer, Buzz, 33; Daniels', 33; 
Surface, 34 

Planes, Core-box, 27; Flexible 
faced, 27; Rabbet, 27; Rout- 
ing, 27; Round soled, 27 

Plates, Center, 36; Dowel, 48 
Dovetail, 79; Match, 64, 83 
Rapping and Drawing, 48 
Stripping, 62 

Points, Trammel, 24 

Propeller, pattern, 81, 106 

Putty fillet, 50 

Qualifications of a pattern-maker, 

3 
Quarter sawing, 44 

Rabbet plane, 27 

Rammers, 7 

Ramming, Jar, 109; Jolt, 109 

Rapping, 16, 18; plates, 48 

Repair of patterns, 10 

Riddle, 7 

Ring core, 99 

Rings, 36 

Round corners, 31-, 48 



114 



INDEX 



Round soled plane, 27 
Routing, cutters, 33; plane, 27 
Rule, Shrinkage, 21 
Rusting patterns, 53 

Sand, Dry, 6; Facing, 7; Green, 

5; Molding, 5; Parting, 8; 

Pattern in, 106; thickness, 105 
Sander, surface, 34 
Sandpaper, 51 
Sawing, Bastard, 44; Quarter, 44; 

Straight, 44 
Saw, Band, 32; Circular, 32; Jig, 

32 
Screw chuck, 36 
Screws, 47 

Sectional patterns, 73 
Segments, 79 
Shellac, 52, 88 
Shoot board, 26 
Shrinkage, 13; Double, 21; rule, 

21; Unequal, 14 
Sieve, 7 
Sizing, 46 

Skeleton pattern, 61, 73, 102 
Small pattern, 74 
Specialization, 1, 39, 108 
Spindle, 103 
Spirit varnish, 52 
Split pattern, 56 
Sprue, 8 

Spur gear pattern, 84 
Square, Center, 23 
Standard pattern, 10 
Staves, 80 
Stopping off, 81 
Storage of patterns, 107 
Stove plate pattern, 30, 57 
Straight, core print, 66; sawing, 

44 



Strains, Cooling, 48 
Strickle, 61 
Strike, 61, 102 
Stripping plate, 18, 62 
Surface, planer, 34; sander, 34 
Sweeps, Inside, 103; Outside, 104 
SweUs, 17 

Table, Cast iron, 21 

Tacks, 47 

Taper, 16 

Tapered core print, 65 

Tempering, 5 

Templets, Form, 41; Marking, 41 

Temporary pattern, 10 

Thickness calipers, 30; Sand, 105 

Thin pattern, 30 

Tool, for cornering, 31; for large 
arcs, 25; for laying out hex- 
agon, 25; for pattern-maker, 20; 
Hook, 36 

Trammel, Coping, 25; points, 24 

Trimmer, 32 

Tripod, 35 

Types of patterns, 54 

V blocks, 25 
Varnish, 52; Spirit, 52 
Ventilation, 37 
Venting, 8 
Vise, 21 

Warping, 43 
Wash, Black, 92 
Wax, fillet, 49; gun, 50 
Weight of castings, 89 
Winding drum pattern, 106 
Wire, Vent, 8 
Wood fillet, 49 
Worm pattern, 82 



THE WILEY TECHNICAL SERIES 



EDITED BY 

J. M. JAMESON 



A series of carefully adapted texts for use in technical, 
vocational and industrial schools. The subjects treated 
will include Applied Science; Household and Agricultural 
Chemistry; Electricity; Electrical Power and Machinery; 
Applied Mechanics; Drafting and Design; Steam; Gas 
Engines; Shop Practice; Applied Mathematics; Agriculture; 
Household Science, etc. 

The following texts are announced; others are being 
added rapidly: 

ELECTRICITY 

THE ELEMENTS OF ELECTRICITY; For Technical Students. 
By W. H. Timbie, Head of Department of Applied Science, 
Wentworth Institute. Small 8vo, xi+556 pages, 415 figures. 
Cloth, $2.00 net. 

THE ESSENTIALS OF ELECTRICITY; A Text-book for Wire- 
men and the Electrical Trades. By W. H. Timbie, Wentworth 
Institute. 12mo, flexible covers, pocket size, xiii+271 pages, 
224 figures. Cloth, $1.25 net. 

CONTINUOUS AND ALTERNATING CURRENT MACHIN- 
ERY. By Professor J. H. Morecroft, Columbia University. 
Small 8vo, ix-f 466 pages, 283 figures. Cloth, $1.75 net. 

ALTERNATING CURRENTS. By W. H. Timbie, Head of Depart- 
ment of Applied Science, Wentworth Institute, and H. H. Higbie, 
Professor of Electrical Engineering, University of Michigan. 
(In press.) 



ELECTRIC LIGHTING. By H. H. Higbie, Professor of Electrical 
Engineering, University of Michigan. {In 'preparation.) 

INTRODUCTION TO INDUSTRIAL ELECTRICITY. By W. H. 

Timbie, Head of Department of Applied Science, Wentworth 
Institute. {In preparation.) 

HEAT AND HEAT ENGINEERING 

HEAT; A Text-book for Technical and Industrial Students. By 

J. A. Randall, Instructor in Mechanics and Heat, Pratt Institute. 
Small 8vo, xiv+331 pages, 80 figures. Cloth, $1.50 net. 

GAS POWER. By C. F. Hirshfeld, Professor of Power Engineering, 
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Instructor, Department of Power Engineering, Cornell University. 
Small 8vo, viii+198 pages, 60 figures. Cloth, $1.25 net. 

STEAM POWER. By C. F. Hirshfeld, Professor of Power Engi- 
neering, Sibley College, Cornell University, and T. C. Ulbricht, 
formerly Instructor, Department of Power Engineering, Cornell 
University. {In preparation.) 

HEAT AND LIGHT IN THE HOUSEHOLD. By W. G. Whitman. 
State Normal School, Salem, Mass. {In preparation.) 

MECHANICS 

ELEMENTARY PRACTICAL MECHANICS. By J. M. Jameson, 
Pratt Institute. Small 8vo, xii+321 pages, 212 figures. Cloth. 
$1.50 net. 

MECHANICS FOR MACHINISTS. By R. W. Burnham, Erasmus 
Hall High School, Brooklyn, Instructor in Evening Machine Work» 
Pratt Institute. {In preparation.) 

MATHEMATICS 

PRACTICAL MATHEMATICS. By C. R. Dooley, Westinghouse 
Electric and Manufacturing Company, Pittsburgh. {In prepara- 
tion.) 

A SHOP MATHEMATICS FOR MACHINISTS. By R. W. 

Burnham, Instructor in Machine Work, Pratt Institute Evening 
School. {In preparation.) 



AGRICULTURE 

POULTRY. By Professor J. C. Graham, Massachusetts Agricultural 
College. (In preparation.) 

SOILS. By Professor A. G. McCall, Ohio State University. (In 
preparation. ) 

AGRICULTURAL CHEMISTRY. By Professor T. E. Keitt, 
Clemson Agricultural College. (In preparation.) 

INJURIOUS INSECTS. By Dean E. D. Sanderson and Professor 
L. M. Peairs, West Virginia University. (In preparation.) 

AGRICULTURAL DRAFTING. By Charles B. Howe, M.E. 
4to, 46 pages, 45 figures, 22 plates. Cloth, $1.25 net. 

STUDIES OF TREES. By J. J. Levison, Forester, Park Depart- 
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FIELD MANUALS IN AGRICULTURE 

A carefully selected series of laboratory and field studies, with 

supplementary theory and information for classroom use. 4to; 

loose leaf, or bound in paper covers as preferred. 

Studies of Trees: Their Diseases and Care. By J. J. Levison, 
M.F., Lecturer on Ornamental and Shade Trees, Yale University 
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Exercises in Farm Dairying. By Professor C. Larsen, De- 
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Exercises in Poultry Raising. By Professor J. C. Graham, 
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Market Gardening. By Professor F. L. Yeaw, Oasis Farm 
& Orchard Company, Roswell, New Mexico. Formerly Pro- 
fessor of Market Gardening, Massachusetts Agricultural College. 
(In preparation.) 

Studies of Insects. By Dean E. D. Sanderson and L. M. 
Peairs, West Virginia University. (In preparation.) 

Farm Crops and Soils. By Professor A. G. McCall, Depart- 
ment of Agronomy, Ohio State University. (In preparation.) 

Exercises in Agricultural Chemistry. By Professor T. E. Keitt, 
Clemson Agricultural College. (In preparation.) 



THE LOOSE LEAF LABORATORY MANUAL 

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Exercises in General Chemistry. By Charles M. Allen, 
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compounds. 4to, 62 pages, 61 exercises. 

Selected exercises as desired, to fit an ordinary binder, two cents 
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Exercises for the Applied Mechanics Laboratory. By J. P. 

Kottcamp, M.E., Instructor in Steam and Strength of Materials, 
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tables. 

Selected exercises as desired, to fit an ordinary binder, two cents 
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Wiring Exercises. By H. A. Calderwood, Carnegie Institute 
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Quantitative Chemical Analysis. By Charles M. Allen, Head 
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Exercises in Industrial Chemistry. By Dr. Allen Rogers, 
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Technical Chemical Analysis. By R. H. H. Aungst, Instructor 
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Qualitative Chemical Analysis. By C. E. Bivins, Instructor in 

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Elementary Electrical Testing. By Professor V. Karapetoff, 
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Exercises in Mechanics. By J. M. Jameson, Girard College; 
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Exercises in Heat. By J. A. Randall, Instructor in Mechanics 
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Exercises in Electricity, A. C. and D. C. By W. H. Timbie, 
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PATTERN MAKING. By Frederick W. Turner and Daniel 
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TOOL MAKING. By W. J. Kaup, Westinghouse Electric and 
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A SHOP MATHEMATICS FOR MACHINISTS. By R. W. 

Burnham, Instructor in Machine Work, Pratt Institute Evening 
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DRAFTING AND DESIGN 

AGRICULTURAL DRAFTING. By Charles B. Howe, M.E. 
4to, viii+63 pages, 45 figures, 26 plates. Cloth, $1.25 net. 

ARCHITECTURAL DRAFTING. By A. B. Greenberg and 
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THE LOOSE LEAF DRAWING MANUAL. Reference and 
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